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LIBRARY 

OF   THK 

UNIVERSITY  OF  CALIFORNIA. 


OF" 


§., 
Accession  Class 


HANDBOOK 


FOR  THE 


USE  OF  ELECTRICIANS  IN  THE  OPERATION  AND  CARE 


OP 


Electrical  Machinery  and  Apparatus 


OF   THE 


U.  S.  SEACOAST   DEFENSES, 


BY 


GEO.  L.  ANDERSON,  A.  M. 
CAPTAIN,  U.  S.  ARTILLERY. 

/-*  tr 


PREPARED  UNDER  THE  DIRECTION  OF  THE  LIEUTENANT  GENERAL 
COMMANDING  THE  ARMY. 


D.  VAN  NOSTRAND  CO. 

23   MURRAY   STLEET,   NEW  YORK. 

U.  S.  GOV'T  PRINTING  OFFICE, 
1902. 


PREFACE. 


The  installation  and  management  of  the  electric  machinery  in  United  States 
battleships  merit  the  attention  of  electricians  in  forts.  Its  character  and  object 
in  the  two  situations  are  similar,  and  the  conditions  of  dampness,  limited  space 
changing  personnel  and  reliability  are  equally  severe. 

Every  implement  or  portion  of  the  fortification  plant  must  be  simple,  certain 
in  operation,  effective,  proved  in  the  industries  as  standard  in  its  class,  and  it 
should  only  be  intrusted  to  the  care  and  management  of  an  efficient  engineer. 
To  be  efficient  he  must  have  ambition,  intelligence  and  the  skill  gained  by  care- 
ful handling.  The  good  order  and  working  of  his  machinery  at  all  times  furnish 
the  only  reliable  testimonial  regarding  his  fitness. 

The  preparation  of  the  Handbook  was  suggested  and  aided  by  the  electricians 
of  the  class  of  1900,  Fort  Monroe.  It  contains  in  full  the  latest  instructions 
issued  by  designers  and  constructors.  The  portion  relating  to  land  and  sea 
mines  is  intended  for  separate  publication.  The  diagrams  were  drawn  by  First 
Sergt.  Karl  P.  Runa.  Notice  of  errors  in  this  first  edition  will  be  thankfully 
received. — G.  L.  A. 

Boston,  1902. 

(3) 


96698 


1.  United  States  Navy  D.  C.  Set  Constructed  by  General  Electric  Company.  5 


HANDBOOK  FOR  ELECTRICIANS. 


SPECIAL  INSTRUCTIONS  TO  ELECTRICIANS. 


1.  Your  special  duties  are  to  secure  the  cleanliness  and  the  best  working  order 
of  every  part  of  the  fortification  electrical  equipment  given  to  your  care,  whether 
it  be  a  Schukert  60-inch  projector  or  a  glass  insulator. 

2.  Upon  taking  charge  of  a  plant,  inspect  it  very  carefully,  and  for  your  future 
protection,  in  a  letter  for  file  report  everything  found  not  in  order,  even  to  the 
tool  marks  on  the  machinery. 

3.  For  ten  days,  if  practicable,  the  retiring  engineer  should  operate,  in  your 
presence,  all  apparatus  to  be  turned  over  and  you,  in  turn,  in  his  presence. 

4 .  Take  written  notes  in  your  notebook  of  the  information  he  gives  you.     Secure 
all  diagrams,  plans  and  instructions  relating  to  the  machinery. 

5.  Keep  posted  on  boards,  or  in  frames,  in  a  lighted  and  frequented  place  as 
soon  as  convenient : 

(1)  Oil  Engine  Directions  obtainable  from  The  De  la  Vergne  Companv, 
East  138th  Street,  N.  Y. 

(2)  The  exact  order  of  operating  valves  and  switches  in  starting,  running 
and  stopping  made  out  by  yourself. 

3)  Instructions,  Electric  Storage  Battery  Company,  Philadelphia,  Pa. 

4)  Diagram  of  pipe  connections,  Engineer  Office  or  yourself. 

5)  Wirings  of  dynamo  and  switch  board,  Engineer  Office  or  contractor. 

( 6 )  Blue  print  of  emplacements  showing  wires,  lamps,  etc. ,  Engineer  Office. 

(7)  Diagram  of  search-light  connections,  General  Electric  Company  or 
Engineer  Office. 

(8)  Diagram  of  each  outside  independent  circuit  under  your  charge. 

6.  Take  care  of  the  equipment  in  the  following  order  of  importance : 

(1)  Storage  battery.  (9)  Firing,  night  apparatus. 

(2)  Steam  boiler.  (10)  Telephones. 

(3)  Generating  set,  steam  or  oil.  (11)  Telegraphs. 

(4)  Switchboard.  (12)  Night  signals. 

(5)  Searchlight.  (13)  Anemometers. 

(6)  External  and  internal  wiring.  (14)  Lines. 

(7)  Lamps  and  outlets.  (15)  Electric  bells. 

(8)  Motors  and  hoists. 

7.  Keep  all  machinery  rooms  clean,  dry,  ventilated  and  well  lighted ;  all  sur- 
faces free  from  rust  and  dust,  even  if  a  banked  fire  or  a  kerosene  burner  is 
necessary. 

8.  Do  not  delay  work  or  repairs  because  exactly  what  you  need  is  not  at  hand. 
Proceed  with  that  which  is  obtainable  and  do  the  best  thing  possible  so  as  to 
avoid  making  excuses.     Even  a  good  excuse  is  unfortunate. 

9.  Make  timely  requisitions  for  only  the  necessary  and  the  best  stores.     Use 
best  mineral  oil  only. 

10.  If  boiler,  engine,  dynamo  or  any  iron  piece  or  tool  is  to  remain  unused,  its 
polished  surfaces  will  be  thoroughly  cleaned  in  full  light  in  a  dry  room  on  a  dry 
day  and  covered  with  a  thick,  uniform  coat  of  cosmic,  with  25  per  cent  of  resin 
added  if  interval  will  be  long.     Every  three  months  clean  off,  repolish  and  re- 
new. 

11.  "Prevention"  is  the  rule  for  machinery  troubles,  not  "Cures." 

12.  In  case  of  accident,  "the  other  man  "  can  not  be  pleaded  by  the  electrician. 
The  clearest  evidence  regarding  his  capacity  is  furnished  by  a  single  boiler 
fixture  leaking,  dirty  water,  incrustation  or  corrosion  in  boiler,  an  unsteady 

(5) 


6  HANDBOOK   FOR   ELECTRICIANS. 

steam  gauge,  water  glass,  or  fire,  an  unusual  noise  in  engine,  a  hot  bearing  or 
coil,  a  scratched  or  sparking  commutator,  an  oil  engine's  chronic  cough  or  thick 
exhaust,  density,  voltage  or  gassing  of  storage  cells  not  uniform,  battery  stand- 
ing at  low  voltage,  burn-outs  and  tool  marks  on  search  light  or  other  apparatus, 
dust,  rust,  or  damp  on  any  part,  unsoldered  joints  or  leaky  circuits,  and  by  other 
things. 

13.  A  neat  and  well-fitting  uniform  will  invariably  be  worn  outside  of  the 
emplacements. 

14.  Always  charge  a  storage  battery  at  its  given  normal  rate  to  full  charge 
(density,  1.200;  voltage,  2. 5  per  cell);  do  not  discharge  above  the  normal  rate 
except  in  emergency,  and  never  below  density  of  1.175  and  voltage  of  1.8  per 
cell. 

15.  Keep  density,  voltage  and  gassing  of  all  cells  uniform.     To  cover  plates 
£  inch,  water  (or  solution,  1.400,  rarely)  is  added  at  the  top  directly  after  charg- 
ing begins.     If  little  used,  the  battery  is  partially  discharged  and  regularly 
charged  once  each  week. 

16.  Blow  off  boiler  in  starting  at  10  pounds  from  water  high,  one  or  two 

fauges ;  of tener  if  necessary.     Maintain  uniform  fire,  water  level,  and  pressure, 
requently  inspect  fire  tubes  for  dirt,  and  boiler  interior  for  deposit  and  corrosion. 

17.  Handle  all  machinery  and  apparatus  with  great  care.     Let  their  loads  be 
increased  and  decreased  uniformly  and  slowly.     Guard  against  sudden  rise  of 
temperatures.     Never  hesitate  to  allow  a  machine  to  take  its  full  load  under 
these  conditions,  but  not  to  exceed  it. 

18.  An  engine  is  always  started  as  slowly  as  possible.     A  good  engineer  turns 
valves  and  switches  deliberately  while  watching  the  effect ;  his  order  of  starting 
and  stopping  is  always  the  same. 

19.  Keep  exposed  conduit,  cut-out,  switch,  junction  and  lamp  boxes  cleaned 
and  painted,  and  all  openings  tightly  sealed,  so  that  the  whole  system  is  essen- 
tially air-tight. 

20.  For  more  complete  information,  electricians  are  referred  to  Crocker's  (two 
volumes)  Electric  Lighting,  Sheldon's  Dynamo  Electric  Machinery,  General  Elec- 
tric Company's  Bulletins  and  Instructions,  Westinghouse  Company's  Bulletins, 
Dawson's  Electric  Traction,    Treadwell's  Storage    Battery,  Goldingham's  Oil 
Engines,  Miller's  Telephony,   Maver's  Telegraphy,  Cushing's  Wiring,  Stroni- 
berg's  Steam  Engine,  Hawkins'  Catechisms  of  Electricity  and  Steam  Engine. 

21.  The  efficiency  of  all  your  machinery  was  long  ago  proved.     The  opinions, 
sometimes  heard,  that  search  lights,  for  instance,  can  not  be  controlled  from  a 
distance,  that  storage  batteries  are  inefficient,  that  telephones  near  guns  are 
inoperative,  that  oil  engines  and  submarine  mines  are  unreliable,  result  from 
the  kind  of  knowledge  which  is  dangerous. 

22.  In  more  than  nineteen  cases  out  of  twenty  in  which  a  standard  machine  or 
apparatus,  properly  installed,  fails,  the  fault  rests  with  the  attendant. 

23.  Remember  that  if  there  is  any  portion  or  piece  of  the  fortification  electrical 
equipment  under  your  charge  not  in  perfect  working  order,  or  not  clean,  and  not 
reported  as  irreparable,  and  if  you  being  for  duty,  are  working  less  than  ten 
hours  daily  on  week  days,  you  will  be  held  blamable. 


[.—HANDLING  AND  CARE  OF  STEAM  FIRE-TUBE  BOILERS. 


(A)    RAISING    STEAM. 

1.  To  start  the  fire  in  a  small  furnace,  clean  the  grate  of  clinkers  and  the  pit 
of  ashes.     See  that  grate  works  freely.     Cover  it  evenly  with  shavings  and 
wood  and  light  the  fire.     Tv'hen  the  upper  stratum  of  hard  wood  is  blazing  well, 
throw  on  a  uniform  2-inch  layer  of  soft  coal,  closing  furnace  and  opening  the  pit 
doors.     When  the  coal  is  red,  add  a  second  similar  layer.     A  third  feeding  should 
leave  a  greater  depth  of  coal  around  the  sides  than  in  the  center. 

2.  If  the  furnace  is  large,  cover  the  grate  all  over  with  a  2-inch  layer  of  hard 
coal,  except  a  space  in  front  for  wood  and  shavings.     Cover  the  coal  at  the  back 
with  a  little  heavy  wood  and  light  the  fire.     Add  coal  to  the  upper  hard  wood 
when  aglow,  as  above,  and  so  continue. 

3.  Regulate  coal  and  draft  for  at  least  one  hour's  rise  to  full  pressure  in  a  small 
warm  boiler,  two  hours  for  a  small  cold  water  boiler  and  five  or  six  hours  for  a 
larcre  cold  boiler. 


Horizontal  Boiler  for  a  Stationary  Engine. 


2.  Horizontal  Return  Fire-Tube  Steam  Boiler. 

4.  After  lighting  the  fire  see  that : 

(a)  Gauge  glass  agrees  with  gauge  cocks  and  is  not  choked. 

(b)  Water  stands  to  upper  gauge  at  least. 

(c)  Safety  valve  is  in  working  order  by  raising  it  once  or  twice. 

(d)  Steam  feed,  throttle,  and  blow-off  cocks  are  closed. 


(e)  Pump  is  oiled. 
(/)  ~ 


\j  i  Upper  gauge  is  temporarily  open  to  equalize  the  pressure  within. 
5.  At  10  to  15  pounds  pressure  blow  off  to  second  gauge  to  drive  out  mud  and 
create  circulation  for  even  temperature. 

(B)  FIRING. 

1.  Before  opening  the  furnace  door  have  plenty  of  coal  at  hand — no  piece 
larger  than  the  fist.     Spread  the  coal  by  throwing  to  the  rear  first  and  so  on  to 
the  front  in  a  thin  uniform  layer.     Most  firemen  heap  on  too  much  fresh  coal. 

2.  The  thickness  of  coal  fire  is  from  5  to  8  inches.     If  the  necessary  thickness 
makes  too  hot  a  fire,  reduce  the  grate  area  by  putting  in  fire  brick,  8  inches  high, 
around  the  sides  of  the  furnace. 

3.  If  the  fire  burns  unequally,  fill  the  vacant  spots.     Allow  no  air  holes  in  the 
bed  of  fuel. 

4.  The  cleaning  tools  are:  The  hoe  for  pulling  or  pushing  the  fire  over  the 
bars,  slice  bar  for  breaking  up  the  fire,  clinker  hook  and  the  T-bar  for  raking 
lengthwise  of  the  bars  beneath  the  fire  to  cause  the  ashes  to  fall  through,  and 
scoop  shovel. 

5.  Clean  or  rake  the  fire  as  rarely  and  as  quickly  as  possible,  but  always  when 
clinker  and  ash  are  closing  the  grate,  usually  two  or  three  times  a  day  if  coal  is 

(7) 


8  HANDBOOK    FOR    ELECTRICIANS. 

hard.     Dark  spots,  heavy  smoke,  and  blue  flame  give  warning.     But  leave  the  fire 
alone  so  long  as  it  is  at  uniform  glow  and  its  light  shows  in  the  ash  pit  beneath. 

6.  -To  clean  a  fire,  have  plenty  of  water  in  the  boiler,  open  damper  and  one  fur- 
nace door,  pack  half  of  the  fire  to  one  side,  raking  out  the  dead  clinkers  and  ash ; 
then  move  the  whole  fire  to  the  exposed  grate  and  clean  the  other  half ;  finally 
spread  the  fire  evenly  and  throw  on  fresh  dry  coal.     Cleaning  reduces  the  depth 
of  fire  and  lowers  the  boiler  pressure.     Shaking  the  grate  is  the  best  way  to  clean 
when  it  can  be  done. 

7.  The  most  effective  and  economical  fire  is  moderately  thick,  steady,  uniform 
and  regulated,  as  far  as  possible,  by  the  chimney  damper.     Enough  air  should  be 
admitted  above  the  fire  through  the  door  air  holes  to  consume  the  rising  gases 
and  thereby  increase  the  heat.     With  a  steady  fire  the  combustion  is  more  per- 
fect and  there  are  less  clinkers,  less  cleaning  and  less  cold  air. 

8.  The  construction  of  a  damper  should  not  admit  its  closing  the  chimney 
entirely,  as  gases  may  otherwise  collect  in  the  flue  and  cause  explosion. 

9.  To  bank  a  fire,  have  three  gauges  of  water.     Allow  fire  to  get  low,  clean 
and  push  it  to  the  rear  in  a  compact  pile  and  cover  it  thickly  with  small  coal  or 
wet  ashes.     Leave  clinker  and  ash  on  the  front  of  grate.     Leave  fire  doors 
open  and  close  the  pit  doors  tightly  and  the  chimney  damper  partially.     If  the 
fire  is  found  too  cold  the  next  morning  less  grate  should  be  uncovered  and  the 
pile  of  fire  be  less  compact.     Banking  the  fire  preserves  the  boiler  by  keeping  its 
temperature  more  nearly  even,  saves  time  in  starting,  but  is  dangerous  if  not 
properly  done. 

10.  To  start  a  banked  fire,  clean  out  ashes  and  clinker  or  shake  the  grate, 
spread  the  fire  evenly,  feed  a  little  wood  for  draft  and  add  coal  gradually 

11.  Ashes  left  high  in  the  ash  pit  may  cause  warping  or  burning  out  of  grates. 

12.  When  fuel  and  water  are  irregularly  fed,  or  pressure  is  always  changing, 
or  the  safety  valve  is  now  and  then  popping,  or  dampers  and  doors  are  being 
frequently  opened  and  closed,  or  if  there  is  a  leaking  of  water,  steam  or  oil,  or 
room  is  dirty,  the  boiler's  tender  is  outside  of  his  sphere  of  usef illness. 

13.  Give  the  last  two  or  three  minutes  in  a  boiler  room  to  its  inspection  to 
make  sure  that  everything  will  be  left  in  order.     Then  close  and  lock  all  doors 
and  windows. 

(C)  CARE  AXD  MAXAGEMEXT  OF  STEAM  BOILERS. 

1.  The  steam  boiler  is  the  most  important  element  of  an  electric  plant. 

2.  An  indifferent  or  intemperate  fireman  and  a  cheap  boiler  are  alike  dangerous. 

3.  The  first  thing  on  taking  charge  of  a  boiler  is  to  inspect  its  safety-fitting 
and  feeding  apparatus. 

4.  Let  the  ear  aid  the  eye  in  detecting  troubles. 

r>.  Never  exceed  the  working  pressure  given  by  the  builder  or  inspector. 

6.  Never  open  nor  close  a  throttle,  a  blow-off  or  other  steam  outlet  suddenly, 
nor  leave  it  before  it  is  closed. 

7.  Repair  a  leak  or  a  damage  in  boiler  or  fitting  as  soon  as  possible.     See  that 
furnace,  combustion  chamber  and  smoke  flue  are  tight. 

8.  Much  smoke  from  the  chimney  shows  that  combustion  is  not  perfect.     All 
air  must  go  through  the  grate  bars  or  the  little  smoke  burners. 

9.  The  boiler  room  should  be  day  lighted,  well  ventilated,  spacious  and  dry. 
Never  leave  it  while  boiler  is  under  steam. 

10.  Dry  steam  only  is  wanted.     If  a  small  jet  from  the  upper  gauge  cock,  close  to 
the  orifice,  is  transparent  or  even  has  a  grayish-white  color,  the  excess  of  moist- 
ure is  less  than  1  per  cent.     If  the  jet  is  strongly  white,  the  excess  is  2  per  cent  or 
more.     Steam  containing  less  than  3  per  cent  excess  of  moisture  is  fairly  ' '  dry. " 

11.  Empty  a  boiler  working  daily  once  a  fortnight.     If  water  is  muddy  blow- 
out 6  inches  daily  and  use  the  surface  blow-out  more  frequently.     To  avoid 
serious  results  examine  blow-out  and  check  valves  whenever  the  boiler  is  filled. 

12.  Procure  the  manufacturers'  directions  of  boiler  and  its  fixtures. 

1 3.  Blisters  and  cracks  may  occur  in  the  best  boiler  plate.     Then  put  the  boiler 
out  of  service  and  repair. 

14.  In  case  of  low  water,  immediately  open  furnace  doors  and  chimney  damper, 
close  pit  doors  tight  and  quickly  cover  the  whole  fire  with  ashes,  soil  or  coal 
(wet  if  possible).     Leave  all  steam  outlets  as  they  are.     Do  not  draw  fires  until 
the  pressure  has  dropped,  nor  turn  on  feed  water,  nor  start  nor  stop  engine,  nor 
lift  safety  valve  until  the  fires  are  out  and  the  boiler  is  cooling.     If  water  has 
only  just  disappeared  there  is  no  immediate  positive  danger.     If  the  water  gets 
too  high,  carefully  open  blow-off  and  let  out  gradually  a  gauge  of  water. 

15.  Foaming  or  priming  is  due  to  forcing  the  boiler  or  to  small  steam  space 
or  to  other  bad  design  or  to  dirty  or  high  water  or  to  opening  the  throttle 


CARE   OF   BOILERS. 


suddenly.  There  is  rumbling  in  the  boiler,  the  glass  gauge  jumps  up  and  down 
and  there  is  danger  of  water  being  carried  over  with  the  steam  and  of  bursting  the 
cylinder.  Partially  closing  the  throttle  may  stop  it.  If  high  or  dirty  water  is 
the  cause,  blow  off  and  pump.  If  the  foaming  is  violent,  check  the  draft  and 
fires.  The  true  water  level  can  only  be  seen  by  closing  throttle  or  supply-pipe 
valve  long  enough  to  observe. 

16.  If  a  boiler  stands  unused  for  a  few  days,  fill  it  to  the  top ;  adding  a  little 
common  washing  soda  is  excellent.     If  it  remains  idle  for  some  time,  empty  it 
and  dry  thoroughly  with  live  coals  inside  the  man  or  mud  hole,  allowing  draft 
through  the  safety  valve.     Sometimes  quicklime  is  used.     Disconnect  the  feed 
steam  and  blow-off  and  finally  seal  the  boiler  air-tight  by  closing  all  openings  and 
coating  the  joints  with  cosmic.     Finally  coat  the  boiler  and  fittings  with 
linseed  oil. 

17.  A  boiler  must  be  cool  when  filled.    Never  allow  water  from  leaky  joints  or 
other  source  to  come  in  contact  with  the  exterior  of  the  boiler.     Feed  water  should 
enter  in  the  direction  of  the  boiler's  circulation,  and  not  near  a  heated  surface. 

18.  A  good  engineer  maintains  a  steady  fire  burning  as  slowly  as  the  required 
pressure  will  permit,  uniform  height  of  water  at  the  middle  gauge  and  a  uniform 
pressure.     The  safety  valve,  gauge  glass,  injector,  valves,  etc.,  are  always  in 
the  best  working  order  and  constantly  watched.     All  joints,  -connections  and 
packing  are  tight.     He  knows  the  extent  of  scale,  corrosion,  and  soot.     All  of 
his  machinery  and  rooms  are  kept  in  order. 

(D)  THE  STEAM  BOITJER  A!NT>  ITS  FITTIKGS  (FIG.  3). 

1.  Every  steam  boiler  requires  the  best  material,  the  highest  grade  of  workman- 
ship, correct  setting,  economy  of  maintenance,  capacities  for  steam,  water  and 
_.  fire,  heating  surface  to  maintain  the  max- 

imum pressure,  free  circulation  of  water,  all 
parts  accessible  for  cleaning,  and  repairs, 
complete  combustion  of  fuel,  joints  and 
weak  parts  not  exposed  to  fire,  minimum 
repairs,  constant  vigilance,  and  care. 

2.  The  piping  is  water-tight,  smooth  inside, 
direct,  and  so  arranged  as  to  take  up  expan- 
sion and  not  to  collect  water.     All  flanges 
and  fittings  are  carefully  put  together.    Rub- 
ber gaskets  are  essential  between  flanges  to 
prevent  leakage  from  pressures  under  100 
pounds ;  soft  copper  for  higher  pressures. 

(a)  Pipes  conveying  live  steam  are  covered 
with  asbestos  or  other  nonconducting  and 
noncombustible  material,  by  which  the  loss 
of  heat  is  often  reduced  three-fourths. 

(6)  All  valves  of  brass  or  bronze  are  globe 
or  gate,  operating  automatically  or  by  means 
of  an  outside  handle.  Leakage  is  often  caused 
by  dirt  or  sticks  in  the  water.  Never  close  a 
valve  or  a  cock  so  loosely  as  to  leak  nor  so 
closely  as  to  bind.  The  last  half  turn  in  clos- 
ing is  made  very  slowly,  if,  like  the  throttle, 
it  checks  a  heavy  pressure.  Valves  lift  about 
one-fourth  their  diameter. 

3.  The  safety  valve  is  raised  daily  by  hand 
to  guard  against  sticking  or  tampering. 

4.  (Fig.  4.)  The  main  valve  V  is  held  down 
on  the  two  circular  seats  M  and  N against  the 
steam  pressure  by  the  spring  S  acting  on  the 
rod  T.     The  outer  seat  N  is  formed  on  the 
body  A  of  the  valve,  while  the  inner  and 

fcTF'  i   I  y:""!'"!'\1  1  'T^ter=i=H    sma^er  ?eat  M  *s  formed  on  the  upper  edge 
«.    »i>  U     i        i|L      I    °f  a  cylindrical  chamber  B  which  is  con- 
f     ^m^j^f^^.^^     \  nected  to  the  body  A  by  arms  containing  the 

passages  C  C.    The  hollow  chamber  B  forms 
i.  *,  .mote** ;  H,  weight  safety  valve ;   a  guide  for  the  valve  F.    Ordinarily  the  steam 
G,  feed  pipe;  ,s,  steam  space;  p,  pressure  exerts  a  pressure  on  the  annular  space  between 

jraujre ;  c  c  c,  gauge  cocks ;  F,  water  line ;  ft,  M  an<l  jV;  when  the  Valve  rises  a  little  the 
fire  tubes;  N,  feed  pipe  with  stop  valve;  o^n-m  rrichpa  nwr  fh»  «<ant  ATinfr»  fVia  niv  anrl 

M  ar  M,  hand  holes ;  a  a,  stay  bolts ;  F,  fire  steam  rusnes  over  tne  seat  J\  into  the  air,  ana 
box ;  E,  grate ;  D,  ash  pit ;  fc,  ring ;  over  the  seat  M  into  the  chamber  B,  whence 


10 


HANDBOOK   FOR   ELECTRICIANS. 


it  escapes  through  the  channels  C,  C.  The  channels  are,  however,  not  large  enough 
to  allow  the  steam  to  escape  from  the  chamber  as  fast  as  it  enters,  and  hence  the 
pressure  in  the  chamber  rises  and  acts  on  the  area  inside  the  seat  M.  This  addi- 
tional pressure  throws  the  valve  wide  open  and 
quickly  relieves  the  pressure  in  the  boiler. 

(a)  Steam  escaping  from  a  safety  valve  is  a  sig- 
nal of  safety.  It  is  set  to  open  at  5  pounds  above 
the  working  pressure.  Changing,  overloading  or 
neglect  is  dangerous.  About  1  square  inch  of  valve 
opening  is  necessary  for  3  square  feet  of  grate  sur- 
face. 

(6)  To  set  a  weight  safety  valve :  Steam  pressure 
in  Ibs.  X  valve  area  in  sq.  ins.  X  dist.  from  fulcrum 
to  center  of  valve  =  Ibs.  required  to  raise  lever  X 
length  of  lever. 

5.  The  pressure  gauge  is  a  brass  circular  tube  of 
oval  cross  section  having  the  open  end  connected 
with  the  boiler  space  by  a  pipe  so  bent  as  to  retain 
water  in  the  tube.     The  steam  pressure  on  the 
water  tends  to  make  the  oval  section  circular  and 
therefore  to  straighten  the  hoop,  whose  free  and 
closed  end  in  moving  turns  a  pointer  by  means  of 
gearing.     The  pressure  shown  is  that  above  atmos- 
phere. 

It  must  be  accurate  over  the  whole  scale,  should 
stand  at  0  when  there  is  no  pressure  and  agree 
with  the  safety  valve  at  blow-off.  If  not,  compare 
it  at  once  with  another  gauge  and  correct.  The 
length  of  the  invisible  jet  from  the  upper  gauge 
cock  is  a  rough  check. 

6.  The  gauge  glass  is  the  boiler  fixture  most 
closely  watched.     A    majority   of   accidents   are 
attributed  to  a  choked  water  gauge  which  is  never 
to  be  relied  upon,  especially  when  the  boiler  is 
foaming,  unless  verified  by  the  three  gauge  cocks. 
Before  firing  and  occasionally  during  the  run,  blow 

out  the  glass  twice  to  see  that  water  returns  to  the  same  level  and  both  pas- 
sages are  clear. 

Cold  drops  of  water  or  currents  of  air  or  scratches  in  cleaning  are  liable  to 
fracture  the  glass.  Then  close  lower  and  upper  stopcocks,  replace  from  stock 
always  on  hand  by  a  new  glass  and  soft  rubber  gaskets,  taking  care  that  the 
glass  does  not  touch  metal. 

7.  The  three  gauge  cocks  are  tried  many  times  every  day  as  a  check  upon  the 
indications  of  the  glass  and  pressure  gauge  and  are  more  reliable.     The  upper 
cock  should  show  dry  steam ;  the  middle  one,  steam  and  water ;  the  lower,  water 
only. 

8.  The  scum  cock,  for  blowing  out  dirt  from  the  surface  of  the  water,  is  opened 
and  closed  alternately  and  quickly  to  prevent  clogging.     Continue  so  long  as 
scum  appears. 

9.  The  blow-off  cock  of  gun  metal  with  metallic  packing  is  opened  at  least  once 
a  day  to  guard  against  sticking.     To  insure  against  the  blow-off  being  left  open, 
the  handle  is  a  removable  spanner  or  key  which  can  only  be  put  on  or  taken  off 
when  the  cock  is  closed. 

Blowing  down  at  about  10  pounds  pressure  while  raising  steam  drives  out 
impurities  on  the  bottom  and  equalizes  the  temperature  throughout  the  boiler. 
If  the  pressure  is  high,  open  deliberately  and  keep  the  hand  on  the  spanner 
while  watching  the  glass.  Make  sure  to  close  the  cock.  If  water  falls  unac- 
countably in  glass,  look  to  the  blow-off. 

10.  The  feed  pump  (fig.  5)  is  an  engine  to  be  cared  for  and  handled  much 
like  the  main  engine.     It  must  be  simple,  double-acting,  quiet,  without  leaks, 
positive  under  varying  pressure,  and  have  a  suitable  location,  no  dead  center,  a 
full  supply  of  water,  both  a  check  and  a  stop  valve  in  the  delivery  and  a  check 
valve  and  strainer  at  the  suction  extremity. 

(a)  The  pump  end  is  in  good  order  if  the  pet  cock,  when  opened,  shows  full 
stream  at  forcing  and  weak  at  suction.  Streams  on  both  suction  and  forcing 
strokes  show  that  the  pump  valves  are  not  closing.  If  there  is  no  stream,  look 
for  air  leakage  in  the  suction  or  no  water  supply.  If  the  receiving  valve  does 
not  close,  the  pet  cock  shows  hydrant  pressure. 


4.  Pop  Safety  Valve. 


CARE    OF   BOILERS. 


11 


(b)  If  pump  goes  slow,  the  packing  may  be  too  tight  or  suction  may  be  closed 
or  steam  has  fallen.     The  packing  is  tight  enough  if  on  closing  the  delivery 
valve  the  plunger  makes  a  stroke  up  and  down  and  then  stops. 

(c)  If  the  pump  gets  hot,  water  may  be  backing  into  it  past  the  check  valve 
from  the  boiler. 

(d)  If  an  accident  happens  to  a  pump  and  there  is  no  injector,  stop  the  engine, 
close  boiler  valves,  draw  the  fire,  raise  the  flue  caps,  and  close  the  damper. 

(e)  If  the  suction  pipe  leaks,  wrap  sheet-rubber  over  the  opening  and  bind  it 
tight  with  string  or  copper  wire  as  a  temporary  repair. 

(/)  A  steam  boiler  requires  both  a  pump  and  an  injector,  each  capable  of  sup- 
plying 1  cubic  foot  of  water  per  horsepower  per  hour. 


END  VIEW  OF  STEAM  CYLINDERS 


PISTON  PATTERN  WATER  END 


Steam   cylinder    (No.  1  aud 

No.  2). 

Stfiiin-cvliiidcr  head. 
Slide  valve. 
Valve-rod  nut. 
Valve  rod. 
Valve- rod  gland. 
Valve-rod  head. 
Steam  chest. 
Steam-chest  cover. 
Steam  pipe. 
Piston  ring. 
Piston  follower. 
Piston-follower  bolts. 
Piston  body. 
Piston  tongue. 
Piston-tongue  spring. 
Piston-tongue  bracket. 
Pjston-rod  stuffing  box. 
Piston-rod  stuffing-box  gland. 
Steam-cylinder  foot. 
Exhaust  flange. 


5.  The  Worthington  Pump. 

23.  Piston  rod. 

24.  Valve-rod  head  pin. 

25.  Valve-rodlink(lougorshort). 
26o.  Long  lever. 

27a.  Short  lever. 

276.  Fork  end. 

28.  Rock-shaft  key. 

29.  Upper  rock  shaft. 

30.  Lower  rock  shaft. 

31.  Crank  pin. 

32.  Spool. 

33.  Spool  position  pin. 

34.  Spool  key. 

35.  Cradle. 

36.  Cross  stand. 

37.  Blow  cock. 

38.  Water  cylinder. 

39.  Water-cylinder  head. 

40.  Plunger. 

41.  Plunger    ring    or    cylinder 

lining. 


42.  Casing. 

43.  Binder. 

44.  Plunger  hub. 

45.  Water-cylinder    hand-hole 

plate. 

46.  Force  chamber. 

47.  Force-chamber    hand-hole 

plate. 

48.  Valve  guard. 

49.  Valve  spring. 

51.  Valve. 

52.  Valve  seat. 

53.  Delivery  tee. 

64.  Air  chamber. 
55.  Suction  flange. 

57.  Piston  nut. 

58.  Plunger  nut. 

61.  Water-cylinder  foot. 

63a.  Solid  water  piston  ring. 

65.  Packed  water  piston  body. 

66.  Packed  water  piston  follower. 


12 


HANDBOOK   FOR   ELECTRICIANS. 


11.  The  injector  lifts,  heats,  and  forces  the  water  into  the  boiler  but  it  is  not 
so  easily  regulated  to  a  small  continuous  flow  as  the  pump. 

(a)  It  has  four  nozzles:  The  steam  nozzle  4,  through  which  a  jet  of  steam 
from  the  top  of  the  boiler  first  passes;  the  combining  nozzle  Cat  whose  extrem- 
ity the  steam  and  the  water  from  the  supply  unite  ;  the  condensing  nozzle  D 

in  which  the  steam's 
condensation  is  com- 
pleted, and  the  deliv- 
ery nozzle,  seen  just 
above  3,  to  the  bot- 
tom of  the  boiler. 

(6)  There  are  four 
openings  —  steam,  wa- 
ter, overflow  and  de- 
livery. 

(°)  The   Hancock 


40  P 


)  With 
steam 


6.  Injector. 


. 

C  9   ?T  3  7      5Ll/AJl_Llk  force  tt  hot  into  the 

BffH  tir  boiler.     It  has  globe 

«fc  1  i  [  /         valves  at  4,  5  and  3 

QH  fjjj^  I  5  I      I       ^g§  an(l  a  check  and  globe 

valve    to    boiler    not 
shown. 

(I)  To  lift  the  water 
and  to  inject  it,  open 
valves  3,  1,  5  and  4  in 
order.  Steam  rushing 
through  4,  C  and  D 
toward  overflow  3 
drives  out  the  air. 
Water  rises  in  5  to  C 
and  the  steam  jet  is  condensed  by  it  at  D.  The  resulting  hot  water  jet  has  less 
cross  section  than  the  steam,  but  equal  energy  at  the  overflow.  When  the  flow 
of  water  here  appears  steady,  close  1  to  turn  the  stream  through  D,  open  2  one- 
half  turn  and  close  3  to  direct  the  flow  into  the  boiler.  The  ear  will  recognize 
proper  action.  The  jet  into  the  boiler  can  be  somewhat  reduced  by  partly 
closing  the  water  supply  5. 

(n)  To  inject  simply  (the  supply  being  above  the  injector)  leave  1  always 
closed  and  open  3  and  5.  When  cold  water  appears  at  overflow,  open  2  and  4 
and  close  3. 

(in)  Metropolitan,  Rue  and  Korting  are  other  good  injectors  similar  in  action. 

(iv)  Failure  to  act  is  due  to  improper  handling,  leakage  of  air,  water  insuffi- 

cient or  too  hot,  pressure  too  low  or  too  high,  or  to  obstructions  in  the  tubes.     If 

the  stream  breaks  unexpectedly,  look  first  to  water  and  steam  supply  for  the 

cause  of  the  trouble. 

(v)  If  hard  scale  forms  on  the  nozzles,  scrape  it  off  or  soak  the  injector  in  a 
one-tenth  solution  of  muriatic  acid  or  boil  it  in  a  mixture  of  vinegar  and  salt. 

(vi)  All  pipes,  valves  and  fittings  of  pump  or  in- 
jector must  be  air-tight  and  agree  in  size  with  pump 
or  injector  openings.  The  suction  pipe  is  larger  if  long. 
Keep  the  fine  wire  strainer  at  its  extremity  clean. 
Injector  and  pump  require  each  its  own  check  valve  and 
a  stop  valve  in  common  in  the  delivery.  Neither  will 
lift  hot  water.  There  ought  to  be  a  water  heater 
between  the  pump  and  boiler  if  the  supply  is  cold.  Use 
injector  if  the  pump  can  only  inject  cold  water. 

1  2.  A  fusible  plug  (fig.  7)  screwed  into  the  crown  sheet 
of  a  furnace,  may  not  act  unless  examined  and  scraped 
clean  on  both  furnace  and  fire  sides  whenever  the  boiler 
is  cleaned.  R  is  the  fusible  metal  in  the  upper  part  of 
the  plug  P,  so  that  when  it  melts  from  low  water  there 
is  still  water  covering  the  crown  sheet  Q. 


7.  Fusible  Plug. 


13.  Several  manholes  are  placed  in  large  boilers,  and  hand-holes  in  small,  for 
purposes  of  inspection  and  cleaning.  Gaskets  are  liable  to  get  hard  or  to  become 
torn  so  that  at  least  one  extra  set  should  be  kept  on  hand. 

14  The  grate  clogged  with  clinkers  or  ash  stops  the  draft. 


CARE    OF   BOILERS. 


13 


(E)  THE  FEED  WATER. 

The  feed  water  ought  to  be  pure  and  hot.  Rain  water  is  usually  satisfactory ; 
well  water  is  often  good,  sometimes  very  bad  for  the  boiler.  When  the  source 
is  untried  or  the  boiler  is  new,  the  man  or  hand  holes  are  frequently  opened  to 
see  if  incrustation,  corrosion  or  both  have  occurred.  These  maladies  are  the 
two  greatest  evils  that  operate  against  the  life  and  safety  of  steam  boilers  and, 
unless  prevented,  will  burn,  granulate  or  distort  the  plates  and  tubes  or  cause 
pitting,  grooving  or  wasting  which  results  in  explosions. 

1.  INCRUSTATION. 

(a)  Well  water  generally  contains  salts  of  lime,  magnesia,  silica  and  alumina. 
When  the  water  is  heated  under  pressure  they  are  liable  to  separate  from  the 
water  forming  at  first  a  soft  deposit.     Heat  further  bakes  the  sediment  upon 
the  boiler's  interior  into  a  nonconducting  stone-like  or  glass  scale  which  sepa- 
rates the  water  from  the  plates  and  leads  to  dangerous  overheating;  ^-inch 
scale  makes  15  per  cent  more  heat  necessary. 

(b)  To  maintain  90  pounds  pressure,  water  must  be  heated  to  320°  F.,  and  a 
clean  boiler  fire  surface  to  325°  F.     If  |-inch  scale  intervenes,  the  fire  surface 
must  be  raised  to  700°  F.     Above  600°  F.  iron  becomes  granular  and  is  liable  to 
bulge  or  crack  under  pressure. 

(c)  Incrustation  can  be  prevented  (i)  by  an  expensive  purifier  which  heats 
the  water  before  entering  the  boiler  until  the  salts  are  precipitated;  (n)  often  by 
chemicals  of  pure  quality  such,  for  example,  as  caustic  soda  for  lime  carbonate 
deposit,  or  carbonate  of  soda  for  lime  sulphate  deposit,  or  good  kerosene,  etc. , 
with  more  frequent  blow-offs ;  (in)  sometimes  by  frequent  use  of  surface  and 
bottom  blow-offs  alone. 

The  chemicals  (n)  simply  make  the  hard  deposit  soft.  They  should  be  uni- 
formly added  in  weak  solutions  to  the  boiler  by  way  of  the  pump,  gently  at  first, 
and  the  effect  carefully  watched  by  an  experienced  person.  Excess  may  cause 
boiler  leakage.  Let  the  first  trial  be  at  the  rate  of  %  pound  salt  per  horsepower 
per  month,  or  one  quart  daily  of  kerosene  per  100-horsepower.  Avoid  all  nos- 
trums. Where  the  supply  is  poor,  a  good  remedy  lies  in  a  large  cistern  and  a 
wide  roof,  from  which  the  first  water  of  every  rain  is  not  collected. 

(d)  When  the  hard  scale  has  been  once  deposited,  the  most  certain  remedy  is 
to  chip  or  pull  it  off  by  hand. 

(e)  Some  waters  having  magnesia,  etc. ,  throw  down  a  fine  floury  deposit  which 
with  little  grease  from  the  exhaust,  and  under  pressure,  often  strains  seams  and 
rivets,  causes  leaks  and  bulges  furnace  plates.     Oil  filters  and  spare  use  of  oil 
are  remedies. 

2.  CORROSION. 

(a)  Corrosion  is  internal  or  external.  Few  boilers  after  some  service  are 
wholly  exempt  from  pitting,  grooving  or  wasting  away  in  irregular  and  ill-defined 
patches.  Internal  corrosion  (fig.  8)  is  the  most  destructive  of  all  boiler  diseases 
and  serious  enough  to  demand  a  remedy 
at  once  and  subsequent  careful  watch- 
ing. Stay  bolts  and  rivet  heads  are 
sometimes  attacked. 

(6)  It  may  be  due  to  acid  from  vege- 
table matter  in  feed  water,  or  decom- 
position of  acid  salts  in  the  scale,  or 
other  impurity  in  hot  water  under  high 
pressure,  or  to  galvanic  action.  The 
ill  effects  can  generally  be  reduced  by 
pure  soda  ash,  in  solution,  uniformly 
added  by  the  pump.  If  galvanic  action 
is  suspected,  fasten  blocks  of  zinc  into 
good  metallic  contact  with  boiler  parts 
and  near  the  patches.  Change  of  water 
•may  cure.  Or,  let  a  chemist  discover 
and  apply  a  neutralizing  agent. 

(c)  To  prevent  external  corrosion, 

allow  no  water  to  come  in  contact  with  8.  Corrosion  Next  a  Lap. 

the  boiler's  outside,  or  dampness  from 

leaking  to  remain  in  the  seatings  and  coverings.     Finally  coat  with  linseed  oil. 

(d)  A  sensitive  hydrometer,  finely  graduated  above  unity  over  a  short  range, 
will  aid  in  detecting  the  waters  which  cause  scale  or  internal  corrosion. 


14 


HANDBOOK    FOR    ELECTRICIANS. 


(F)    CZjEANING   THE   BOLLER. 

1.  While  cleaning,  watch  for  faults. 

2.  The  heating  surface,  first  of  all,  should  be  kept  clean  on  both  sides.     Never 
allow  scale  or  soot  to  exceed  TV  inch  in  thickness.     A  chisel  may  be  used  for 
scale ;  a  scraper,  chain  or  wire  brush,  and  not  steam,  for  flues. 

3.  The  water  in  the  boiler  is  changed  every  two  or  three  weeks. 

4.  Empty  and  thoroughly  clean  once  in  five  hundred  working  hours,  of  tener 
if  the  boiler  is  new  or  the  water  is  bad,  or  the  work  has  been  intermittent.    The 
interior,  after  it  has  cooled,  is  washed  down  with  a  hose  and  dried,  all  scale  is 
removed  and  the  boiler  again  washed.     A  small  chain  is  sometimes  dragged 
around  the  tubes  to  clean  them.     Before  closing  the  manholes  remove  crust  and 
tools  that  they  may  not  choke  the  blow-off. 

(G)    THE   INSPECTION    OF    A   BOIUSR. 

1.  By  a  legalized  inspector,  once  a  year,  extends  to  every  part  and  fixture  of  the 
boiler,  first  empty  and  then  under  steam,  after  the  defective  parts  have  been 
replaced. 

2.  Boiler,  flues  and  mud  drum  are  first  cleaned  and  dried  in  order  to  be  seen. 

3.  The  inspector  ascertains  the  soundness  and  thickness  of  the  plates  by  the  sound 
and  rebound  of  a  very  light  hammer.     The  hammer  test  is  usually  sufficient. 
He  notes  the  location  and  amount  of  incrustation  and  corrosion,  and  searches  for 
blisters,  cracks,  loose  rivets,  broken  or  corroded  stays,  fractured  joints,  etc.    All 
seams,  head,  and  tube  ends  are  examined  carefully.     A  doubtful  spot  is  exam- 
ined with  the  aid  of  a  magnifying  glass.     Sometimes  a  small  hole  is  drilled 
through  and,  after  inspection,  plugged. 

4.  A  loose  rivet  is  replaced.     A  stay,  brace,  or  fastening  found  defective,  or  a 
tube  cracked  is  taken  out  and  a  new  one  is  put  in.     A  blister  or  a  bulge  is  cut 
out  and  a  patch  is  riveted  inside  if  possible. 

5.  The  hydraulic  test  is  made  when  the  boiler  is  new  or  extensively  repaired 
or  can  not  be  thoroughly  examined  inside  and  out.     Fill  the  boiler  with  water, 
close  all  outlets  and  use  the  force  pump  very  slowly  and  evenly  until  the  pres- 
sure is  one  and  one -half  times  the  working  pressure.     Or  a  gentle  fire  may  be 
started  under  the  filled  boiler  to  get  the  desired  pressure,  but  the  temperature  of 
the  water  should  not  exceed  212°.     There  is  no  danger  of  explosion  if  boiler  is  filled. 

Watch  the  gauge  closely  for  any  drop  in  pressure  due  to  the  boiler's  yielding. 
By  fixing  points  of  sticks  or  wire  close  to  the  outer  surface  of  furnace  sheets, 
shell  and  ends,  any  deformation  due  to  pressure  may  be  detected.  Any  leakage 
in  seams,  rivets  or  joints  is  calked  before  continuing  the  test. 

6.  Under  steam,  the  pressure  gauge  is  compared  with  a  standard  along  its  entire 
scale;  the  safety  valve  is  raised,  operated,  and,  if  necessary,  reset.     Look  for 
leakage  in  cocks,  valves,  joints,  and  all  fixtures,  and  for  any  faulty  action  in 
gauge  glass,  pump  and  injector. 

7.  The  inspections  of  a  boiler  begin  at  its  manufactory  and  continue  so  long  as 
it  is  in  use. 

(H)    EXPLOSIONS. 

About  250  steam-boiler  explosions  occur  annually  in  the  United  States,  mainly 
due  to  preventable  causes.  Vigilance  and  execution  of  the  foregoing  rules  will 
prevent  them.  When  the  first  symptom  of  a  disorder  appears,  apply  the  remedy. 

In  1893,  a  single  American  insurance  company  examined  163,000  boilers,  in- 
spected 67,000,  tested  hydrostatically  8,000  and  found  600  unsafe.  In  all,  133,000 
defects  were  discovered,  of  which  12,000  were  dangerous,  as  classified  below: 


Nature  of  detects. 

Whole 
No. 

Dan- 
gerous. 

Nature  of  defects. 

Whole 
No. 

Dan- 
gerous. 

Deposit  of  sediment 

9,774 

548 

Leakage  around  tubes 

21  211 

o  909 

Incrustation  and  t-cale           ___     ___ 

*18,  3«0 

865 

Leakage  at  seams 

5  424 

482 

Internal  grooving  

1,24!» 

148 

\Viiter  trances  defective 

3  670 

660 

Internal  corrosion  _ 

i;  -j.vj 

907 

ItloW-ollts  defective 

1  620 

425 

External  corrosion  

8,«00 

936 

'    Deficiency  of  water 

204 

107 

Defective  braces  and  stays 

1,966 

1--, 

Safety  valves  overloaded 

723 

203 

Settings  defective- 

:',  n:ij 

m 

Safety  valves  defective 

942 

300 

Furnaces  out  of  shape 

1  r.T.'i 

254 

5  953 

552 

Fractured  plates 

3  532 

640 

115 

115 

Burned  plates  

2  762 

325 

Unclassified  defects 

755 

4 

Blistered  plates 

3  331 

164 

Defective  rivets  _ 

17,415 

1,569 

Total 

122  8'J3 

12  390 

Defective  heads   

l  :;.--: 

350 

CARE   OF   BOILERS.  15 

The  various  causes  are : 

1.  Excessive  pressure,  due  to  carelessness  of  the  engineer  who  ought  to  have 
been  intelligent,  well  paid  and  legalized ;  and  to  defective  pressure  gauge,  safety 
valve  and  observation  of  water  gauge — all  three  combined.     The  working  pres- 
sure should  not  exceed  two-thirds  of  the  water  test  or  one-fifth  the  safe  theoreti- 
cal pressure. 

2.  Overheating  of  plates  due  to  low  water  or  scale.     While  boiler  is  under 
steam  the  water  line  should  always  stand  at  the  middle  gauge,  and  the  water 
glass  should  be  cleaned  and  watched. 

To  stop  scale,  inspect  and  clean  boiler  regularly,  blow  off  sufficiently  often, 
use  the  scum  cock,  seek  the  proper  solvent  and  change  the  water,  if  necessary. 

3.  Corrosion  in  patches  and  holes.     After  some  explosions,  plates  are  found 
wasted  in  places  to  the  thickness  of  paper.     Vertical  boilers  are  more  liable  to 
explode  from  corrosion  at  the  ends  of  tubes.     Keep  boiler  full  of  water  if  it  lies 
idle  a  few  days. 

4.  Bad  construction  in  material,  design,  or  workmanship.     There  is  no  remedy. 
The  prevention  lies  in  purchasing  boilers  from  a  standard  maker.     There  is  only 
one  grade  of  boiler  to  be  selected,  i.  e.,  the  best. 


II.— THE  STEAM  ENGINE. 


The  type  generally  used  in  isolated  plants  is  a  simple,  double-acting,  single- 
slide  or  piston  valve,  automatic  cut-off,  high-speed,  high-pressure,  horizontal  or 
vertical,  direct-connected,  steam  engine.  All  types  involve  similar  principles 
and  require  the  same  kind  of  care. 

(A)  ITS  OPERATION. 

STARTING. 

1.  Drain  water  out  of  steam  feed  pipe  and  close  the  drain. 

2.  Make  sure  that  every  part  of  the  plant  is  in  order. 

3.  See  that  both  cylinder  drains  are  open. 

4.  If  the  engine  is  not  too  large,  turn  it  over  by  hand  to  see  if  it  runs  smoothly 
without  play  and  leave  the  crank  at  45  degrees,  leaning  toward  and  moving  from 
the  cylinder. 

5.  Open  the  throttle  a  small  fraction  of  a  turn  to  drive  out  water  and  to  warm 
the  cylinder  while  oiling. 

6.  In  a  regular  order  fill  the  oil  cups  and  oil  all  bearings,  and  make  sure  that 
oil  is  not  choked  by  gumming  anywhere. 

7.  The  cylinder  must  be  warmed  some  time  to  allow  free  motion  of  the  valve 
and  piston. 

8.  Widen  throttle  slightly  to  start  engine  as  slowly  as  possible  during  the  first 
dozen  turns. 

9.  Bring  engine  to  full  speed  very  gradually,  standing  ready  to  close  instantly 
if  a  blow  is  heard. 

10.  Then  turn  throttle  wide  open. 

11.  Close  the  drain. 

12.  Adjust  the  oil  cup  and  lubricator  feeds,  two  to  five  drops  per  minute 

RUNNING. 

1.  The  engine  should  run  without  noise.     Lost  motion  is  taken  up  gradually 
as  soon  as  it  is  detected. 

2.  The  ear  may  aid  the  eye  in  detecting  troubles. 

3.  Watch  for  heating  especially  in  crank,  crosshead,  cylinder,  stuffing  boxes, 
main  bearings  and  eccentric.     When  found,  ease  away  on  nut  or  key  when 
possible  and  increase  oil  to  which  melted  tallow  may  be  added.     Correct  the 
fault  at  the  first  stop. 

4.  Uneven  speed  indicates  sticking  of  the  valve  or  governor  parts  or  loose 
connections  in  the  valve  motion. 

5.  See  that  oil  cups  feed  properly  and  that  no  bearing  surface  is  dry.     Guard 
against  the  use  of  too  much  oil. 

6.  A  click  in  the  cylinder  from  water  should  be  quickly  recognized.     Open 
both  drains  until  it  stops. 

7.  An  engine  running  requires  constant  vigilance  and  labor  on  the  part  of  its 
attendant.     There  is  no  place  for  company  or  a  chair  in  an  engine  room. 

STOPPING. 

1.  Slow  down  engine  gradually,  especially  if  pressure  is  high,  and  be  deliber- 
ate in  last  half  turn  of  throttle.     Leave  the  crank  on  outer  dead  center. 

2.  Close  all  oil  cups. 

8.  Open  drains  and  loosen  belt. 

(16) 


THE    STEAM    ENGINE.  17 

4.  Feel  crank,  crosshead  and  other  parts  for  heat. 

5.  Clean  the  engine  thoroughly  while  warm. 

6.  Close  the  room  tight,  locking  doors  and  windows,  that  engine  may  cool 
slowly. 

(B)  GENERAL,  CARE  AND  MANAGEMENT. 

1.  Never  attempt  to  adjust  a  key  or  part  without  first  marking  its  original 
position  with  a  pencil  or  a  metal  point. 

2.  After  making  an  adjustment  run  at  first  slowly  on  no  load  and  011  light 
loads.     Experimental  changes  should  never  be  allowed. 

3.  If  the  engine  is  unexpectedly  stopped  and  the  steam  pressure  is  high,  throw 
fresh  coal  on  the  fire,  close  damper  to  grate,  open  the  furnace  door,  and  start 
the  pump. 

4.  Keep  steam  at  uniform  pressure  while  running. 

5.  If  engine  is  new  or  just  overhauled,  run  it  slowly  without  load  and  with 
light  loads  for  hours  to  let  it  wear  to  its  bearings.  ' 

6.  A  cleanly  kept  engine  in  good  order  attests  its  engineer's  capabilities.     All 
bearing  parts  are  kept  free,  smooth,  oiled  and  without  lost  motion. 

7.  The  new  man  gains  all  the  information  possible  from  the  retiring  engineer 
and  should  possess  the  manufacturer's  directions. 

8.  No  loose  garment  should  be  worn  around  an  engine  in  motion. 

9.  Do  not  tinker  with  the  engine.     If  it  is  necessary  to  repair  some  part,  do  it 
thoroughly  and  look  over  all  other  parts. 

10.  Inspect  at  least  once  a  month  for  leakage  in  piston,  valves  and  cocks. 
Watch  gauge  glass  for  leakage  from  boiler  when  engine-  is  not  running.     See  if 
piston  and  valve  rods  are  in  alignment,  if  cylinder  is  scored,  if  all  bolts  are 
secured,  if  shoulders  are  forming  in  the  cylinder,  if  there  is  acid  in  the  oil,  etc. 

11.  If  cylinder,   valve,  rod  or  guide  is  scored,  graphite  put  on  will  fill  the 
scratches  and  may  restore  the  smoothness. 

12.  Always  add  oil  to  the  graphite. 

13.  Packing  allowed  to  become  hard  will  flute  the  rods. 

14.  Packing,  waste,  iron  parts,  etc. ,  temporarily  laid  on  the  floor,  may  carry 
dirt  and  grit  to  the  bearing  parts. 

15.  Every  bearing  surface  requires  a  drop  of  the  best  mineral  oil  applied  not 
often  but  regularly — a  thick  oil  for  cylinder  and  thin  for  other  parts.     Most 
engineers  use  too  much  oil.     Never  allow  surfaces  to  get  dry.     Dirty  oil  from 
boxes  may  be  filtered  and  reused. 

16.  Thin  grease  mixed  with  cylinder  oil  is  the  best  lubricant  for  governors. 

17.  If  there  is  not  a  belt  tightener,  put  the  belt  partially  on  the  pulley  at  rest, 
then  run  it  on  the  engine  pulley  to  be  started  with  very  slow  motion. 

18.  The  practiced  ear  can  generally  tell  if  the  exhaust  is  regular.    If  the  puffs 
are  long  and  short  alternately,  the  exhaust  is  freer  at  one  end  than  the  other. 
One  exhaust  may  be  heavier,  yet  the  two  may  be  equally  timed.     Equalizing 
the  cut-off  and  exhaust  is  a  partial  remedy, 

19.  It  is  difficult  often  to  locate  knocking.      Therefore,  seek  the  place  and 
cause,  but  proceed  cautiously  before  making  any  changes  intended  to  remedy 
the  evil.     It  is  usually  due  to  the  following  causes : 

(a)  Lost  motion  in  crank,  crosshead,  valve  rods,  main  journals,  etc.     Try  the 
hand  on  the  suspected  part  at  rest  or  in  slow  motion. 

(b)  Valve  not  set  or  the  slipping  of  eccentric  which  admits  steam  suddenly; 
if  due  to  valve,  an  indicator  diagram  is  necessary. 

(c)  Engine  out  of  line.     See  remedy  elsewhere. 

(d)  Crank  pin  not  parallel  to  main  shaft.     Disconnect  connecting  rod  from 
crosshead  and  clamp  to  this  end  of  the  rod  a  spirit  level  parallel  with  the  shaft. 
As  the  crank  is  turned  the  bulb  will  show  if  pin  is  not  parallel  with  the  shaft. 

(e)  Leaky  piston  rings,  poor  lubrication,  water  in  cylinder. 

20.  Relief  valve  on  cylinder  is  set  at  5  pounds  higher  than  the  safety  valve. 

21.  Heating  is  due  to  lack  of  good  lubricant;  dirt,  grit,  or  filings  in  journals; 
bearings  too  tight ;  reciprocating  or  revolving  parts  out  of  line ;  improper  fitting ; 
too  heavy  load ;  too  high  velocity ;  too  great  pressure. 

22.  To  feel  for  heating,  at  crank  pin  in  motion,  stand  in  front  of  the  engine 
and  lower  slowly  the  hand,  palm  down,  until  the  crank  barely  touches  it  on  the 
up  stroke ;  or,  starting  from  the  crosshead  end  of  the  connecting  rod,  slide  the 
hand  along  the  rod  to  the  crank. 

23.  Never  permit  the  heating  to  reach  a  degree  uncomfortable  to  the  hand. 
If  it  remains  moderate,  oil  and  wear  may  stop  it. 

1714—2. 


18 


HANDBOOK    FOR    ELECTRICIANS. 


24.  In  case  of  smoke  from  overheating,  slow  down  the  engine  as  quickly  and 
as  far  as  possible,  but  do  not  stop  it  until  the  part  has  cooled.     Then  dismount 
quickly,  clean  off  the  brass  from  the  steel,  and  correct 
the  fault. 

25.  Piston  rings  should  clear  the  cylinder  at  both 
ends  a  fraction  of  their  width  for  smooth  running. 

26.  Remember  that  the  pump  is  a  second  engine. 

27.  If  a  valve  leaks,  clean  it,  reground  the  seat,  but 
do  not  increase  the  pressure. 

(C)  THE  CYLINDER  LUBRICATOR  (Hi}.  10), 

To  refill  with  oil,  close  L,  C  and  K  in  order.  Unplug 
F  to  drain  off  reservoir,  allowing  air  to  enter  at  E, 
Close  F  and  take  out  E  to  fill  with  oil.  Replace  E, 
open  C  and  K,  and  regulate  L  from  two  to  five  drops 
a  minute,  depending  upon  the  qualtity  of  oil  and  the 
amount  of  work. 

If  a  glass  breaks,  close  C  and  K  and  drain  out. 
Loosen  the  packing  nuts,  replace  with  new  glass  and 
gaskets,  taking  care  that  the  glass  does  not  touch  metal. 


(D)  THE  FOUR  CRITICAL  POSITIONS  OF 
VALVE  AND  OTHER  MOVING  PARTS. 

1.  When,  as  in  fig.  11,  the  valve  Xis  in  the  middle 
position,  and  the  eccentric  arm  is  nearly  vertical,  A  a 
is  the  steam  lap  and  B  b  is  the  exhaust  lap  of  the 
valve.     The  lead  of  a  valve  is  the  distance  the  steam 
port  is  opened  at  the  beginning  of  the  crank's  stroke 
(fig.  12).     Full  port  opening  (fig.  15)  occurs  at  the  end 
of  the  eccentric's  stroke. 

2.  Lap,  lead,  or  full  port  angle,  or  arc,  is  that  made 


10.  Sight  Lubricator  to 
Cylinder. 


R,  reservoir,  oil  shown  in  upper  .  ,  . 

half;  c,  upper  valve;  E,  filling  by  either  crank  or  eccentric  while  a  point  of  the  valve 
plug ;  F,  drain ;  K,  discharge  valve ;  travels  over  lap,  lead,  or  full  port  opening. 

gauge  3-  Travel^ total  distance  valve  moves  =  two  times 
length  of  eccentric  arm.  Stroke = total  distance  piston 
moves  =  two  times  length  of  crank.  Angle  of  advance  =  amount  of  angle  the 
eccentric  is  ahead  of  crank. 

4.  If  we  consider  what  takes  place  at  one  port,  say  the  left,  and  on  the  left 
side  of  the  piston  during  one  full  stroke  and  return,  it  will  be  seen  that  there 
are  four  critical  positions  of  valve,  piston,  etc. ,  during  the  one  turn  of  the  fly 
wheel,  say  clockwise,  as  in  figs.  13,  16,  17,  18. 


11.  Laps. 


(1)  Admission  of  steam  begins  when  A  is  at  a  going  to  the  right. 

(2)  Cut  off  of  steam  begins  when  A  is  at  a  going  to  the  left. 

(3)  Release  of  steam  begins  when  B  is  at  b,  going  to  the  left. 

(4)  Compression  of  steam  begins  when  B  is  at  b,  going  to  the  right. 

These  four  events  similarly  occur  on  the  right  side  during  a  stroke  and  return, 
and  so  on. 


THE   STEAM   ENGINE. 


19 


12.  Lead. 


SLIDE  VALVC 


Fig.  13  shows  admission  of  steam  to  head  end  of  cylinder  before  the  end  of  a 
stroke,  in  order  to  form  a  cushion. 


13. 


Iii  fig.  14  the  piston  (also  crank)  is  at  head  dead  center  under  full  boiler  pres- 
sure, and  valve  is  at  lead  by  definition. 


14. 


In  fig.  15  steam  port  is  full  open.     Eccentric  arm  is  at  crank  dead  center. 


In  fig.  16  steam  is  cut  off.  Pressure  on  piston  will  now  be  due  to  expansion 
only  of  the  steam  in  the  cylinder.  Eccentric  makes  nearly  the  same  angle  with 
vertical  through  O,  as  at  admission. 


22F 


16. 


20  HANDBOOK    FOR   ELECTRICIANS. 

In  fig.  17  inside  edge  of  valve  going  to  left  has  reached  port's  inside  ed°-e 
Release  of  steam  or  its  exhaust  to  atmosphere  begins. 


In  fig.  18  inside  edge  of  valve  going  to  right  has  reached  the  port's  inside  edge, 
and  compression  of  steam  in  the  cylinder  follows.  Eccentric  makes  about  the 
same  angle  with  vertical  through  O  as  at  release. 

Admission  (fig.  13)  next  follows,  and  so  on, 


(E)    TO    CONSTRUCT    ACCURATELY    IN    ONE    FIGURE    (19) 
THE   FOUR   CRITICAL   POSITIONS. 


Given,  travel  —  3  inches ;  steam  lap  =  H  inches ;  lead  =  T^  inch,  and  exhaust 
lap  =  i  inch. 

On  H  i  =  3  inches,  draw  eccentric's  circle  m  i  n;  outside,  crank's  circle  M I N. 
Omis  the  eccentric  arm's  position  at  valve's  mid  travel. 

Lay  off  O  E  =  exhaust  lap,  £  inch,  O  L  =  steam  lap,  L  T  =  lead,  erect  verticals 
to  get  points  d,  c,  a,  b,  and  t .  The  radii  Oa,Ol},Oc,  and  O  d  are  by  definitions 
the  positions  of  the  eccentric  at  admission,  cut-off,  release  and  compression. 

d  m  =  c  n  =  exhaust-lap  arc ;  m  a  =  n  b  =  steam-lap  arc ;  a  t  =  lead  arc. 

d  O  m  =  exhaust-lap  angle ;  m  O  a  =  steam-lap  angle ;  a  O  t  =  lead  angle. 

Lay  off  H F  =  a  t,  and  through  F  draw  O  A.  AOa  are  the  positions  of  crank 
and  eccentric  at  admission. 

The  eccentric  is  always  in  advance  of  the  crank  by  an  arc  =  m  a  +  90°  +  a  t, 
or  in  angle  =  m  O  a  +  90°  +  H  0 \F  =  angle  of  advance. 

Steam  lap  O  L  +  full-port  opening  L  i  =  }  valve  travel  =  1£  inches;  full-port 
arc  a  i  =  90°  —  m  a. 

Lay  off  from  b,  arc  b  x  —  m  a  +  90°  +  a  t,  or,  since  b  i  =  a  i  =  90°  —  m  a,  lay 
off  from  i  the  difference  (2  m  a  -f  a  t)  to  get  x.  Bob  are  the  positions  of  crank 
and  eccentric  at  cut-off. 

Lay  off  from  c  arc  c  y  =  m  a  +  90°  +  a  t,  or,  since  arc  c  i  =  90°  -f  c  n,  lay  off 
from  i  the  difference  (m  a  +  a  t  —  d  m)  to  get  y.  C  O  c  are  the  positions  of 
crank  and  eccentric  at  release. 

Lay  off  from  d,  arc  d  z  =  m  a  -f  90°  +  a  t,  or,  since  arc  d  H  =  90°  —  d  m,  lay  off 
from  H  the  difference  (m  a  -j-  a  t  +  d  m)  to  get  z.  D  o  d  are  the  crank  and 
eccentric  positions  at  compression. 

Therefore  the  crank  is— 

At  admission,  the  lead  angle  distant  from  first  dead  center. 

At  cut-off,  two  steam  lap  angles  -f  lead  angle  from  second  dead  center. 

At  release,  steam  lap  -f  lead  —  exhaust  lap  (angles)  from  second  dead  center. 

At  compression,  steam  lap  -j-  lead  -j-  exhaust  lap  (angles)  from  first  dead 
center. 


THE    STEAM   ENGINE. 


19.  Four  Critical  Positions  of  Crank  and  Eccentric  Arm. 


(F)   TO  EQUALIZE  THE  FORWARD  AND  RETURN  STROKES 

OF  THE  PISTON. 


The  foregoing  would  only  be  true  for  very  long  connecting  rods.  The  angular 
position  of  an  actual  rod  (about  six  times  longer  than  the  crank)  delays  the 
events  on  the  stroke  from  the  head  end  and  produces  them  too  early  on  the 

return.  If,  for  instance  (fig.  20),  the  pis- 
ton is  at  A  and  C  when  crank  is  at  the 
dead  centers,  it  will  be  to  the  right  of  B, 
midway  of  A  and  C,  when  the  crank  is 
vertical ;  that  is  to  say,  the  piston  travels 
faster  in  the  head  end  half.  For  a  partial 
remedy  equalize  the  leads  of  the  valve  and 
slightly  alter  one  exhaust  lap  for  equal 
The  valve  position  is  less  disturbed  than  that  of  crank 


20.   Crank  Moves  Uniformly,  Piston 
Does  Not. 


release  and  compression. 

because  the  eccentric  arm  is  relatively  short. 


HANDBOOK   FOR   ELECTRICIANS. 


(G)    EFFECT   OF    CHANGING   STEAM   LAP,   EXHAUST   LAP, 
TRAVEL  AND  ANGULAR  ADVANCE. 


By  increasing. 

Admission. 

Expansion. 

Exhaust. 

Compression. 

Steam  lap 

Begins   later,  ends 

Begins  sooner,  lasts 

Unchanged 

Begins     at     s  a  m  e 

Exhaust  lap  

Travel  or    eccentric 
ami. 

sooner. 
Unchanged  

Begins  sooner,  lasts 
longer. 
Begins  sooner,  pe- 

longer. 
Begins    same,  lasts 
longer. 
Begins  later,  ends 
sooner. 
Begins  sooner,  pe- 

Begins later,   ends 
sooner. 
Begins  later,  ends 
later. 
Begins  sooner    pe- 

point. 
Begins  sooner,  lasts 
longer. 
lii'-ins    later,    ends 
sooner. 
Begins    sooner,    pe- 

riod same. 

riod  same. 

riod  same. 

riod  same. 

(H) 


PRINCIPLE   OF   THE 
MATIC 


WHEEL-GOVERNOR   AUTO- 
CUT-OFF. 


1.  If  the  angle  of  advance  A  O  a  (fig.  19)  is  increased,  full  port  L  i  is  made 
less,  b  approaches  i,  the  cut-off  b  0  occurs  earlier  and  the  period  of  admission  of 
steam  against  the  piston  is  lessened.  But  the  lead  would  thereby  be  increased. 
To  keep  it  the  same,  the  eccentric  arm  is,  by  the  automatic  cut-off,  shortened  at 
the  same  time  the  angle  of  advance  is  increased.  The  valve  travel  is  thus  less- 
ened and  the  lead  is  preserved. 

Or,  admission  may  be  prolonged  by  automatically  decreasing  the  angle  of 
advance  and  increasing  in  effect  the  eccentric's  arm. 

2.  Wheel  governors  accomplish  the 
above  in  different  ways  in  order  to  keep 
uniform    the  speed    under  a  varying 
load — 

(a)  If  load  decreases,  speed  increases, 
governor  weight  is  thrown  out  by -cen- 
trifugal force,  valve  travel  and  admis- 
sion period  are  diminished. 

(b)  If  load  increases,  speed  decreases, 
governor  weight  is  drawn  in  by  the 
spring,   valve    travel    and    admission 
period  are  increased. 

3.  The    governor    (fig.    21)    of    the 
straight-line  engine  affords  a  typical, 
simple,    and  accurate  automatic  con- 
trol of  steam  to  load. 

The  eccentric  is  screwed  to  a  plate, 
A  C,  pivoted  at  a  on  the  fly-wheel,  re- 
volving clockwise.  As  the  weight  W 
flies  out,  the  end  d  of  the  eccentric 
arm  is  shifted  about  a  as  a  center 
toward  c  by  the  links  1 1  moving  with 
the  arrow  against  the  spring  S.  Govern  - 

ors  usually  have  two  opposite  weights  actuating  the  eccentric  arm  like  the  above. 
Fig.  22  gives  by  the  same  letters  the  relative  positions  above  of  crank  h  c, 

eccentric  arm  c  d,  center  of  shaft  c  and  center  of  governor  motion  a.     Angle  of 

advance  =  h  c  d.     Describe  arc  through  d  to  center  a. 

When  too  high  speed  throws  W  outward,  the  free 

end  of  the  eccentric  arm  is  moved  to  some  point  e, 

the  angle  of  advance  becomes  h  c  e,and  the  eccentric's 

length  c  e.     The  valve  travel  is  shortened,  the  lead 

is  preserved,  cut-off  occurs  earlier,  admission  of  steam 

and  speed  are  less. 

4.  To  adjust  the  governor  for  increase  of  speed, 
slide  the  weights,  if  movable,  toward  the  center 
equally ;  or  tighten  the  springs  equally ;  note  that  the 
spirals  do  not  touch  each  other.     To  run  slow,  loosen 
them,  but  seldom  more  than  an  inch. 

5.  To  make  sure  that  the  tensions  on  both  springs  remain  equal,  count  the 
turns  made  by  the  nuts  in  tightening,  or  listen  to  the  sounds  of  the  springs  when 
struck  after  tightening. 

6.  For  larger  changes,  procure  other  weights  and  springs.     The  governor  can 
usually  be  changed  to  run  reverse.     If  it  ever  works  irregularly,  look  for  a 
gummed  or  dry  joint  or  a  surface  that  binds. 


c  h  =  general  direction  of  crank  and  eccentric  rod 
c  d  =  eccentric  arm. 


22.    Wheel    Governor's    Auto- 
matic Control  of  Steam 
Valve. 


OF  THE 

UNIVERSITY 

OF 


22a.  Sturtevant  Double  Engine. 


THE    STEAM    ENGINE.  23 

(I)    A   FLTLIj   INSPECTION  OF   AN   ENGINE. 

A  full  inspection  extends  to  proving  the  level  of  its  base ;  the  alignment  of 
cylinder,  shaft,  crank  pin  and  guides ;  of  valve  rod  and  eccentric ;  trueness  of 
cylinder  bore,  fly  wheel,  and  bearing  surfaces;  equality  of  clearance;  the  fit 
of  piston  to  cylinder ;  of  crosshead  to  guides ;  of  connecting-rod  brasses  to  crank- 
pin  and  crosshead  .-journals ;  of  main  shaft  to  its  bearings ;  of  packing  to  rods ;  the 
setting  and  critical  positions  of  the  valve ;  lengths  of  rods  and  the  general  order. 

Tools  required :  Spirit  level,  inside  calipers,  plumb  line,  straightedge,  ruled 
square,  very  fine  stout  string,  stick  slotted  for  a  cylinder -head  bolt.  The  rules 
given  below  for  a  horizontal  engine  suggest  the  course  for  a  vertical. 

1.  To  prove  the  base  level,  apply  the  spirit  level  in  two  positions  at  right 
angles  on  the  base,  always  reversing  the  level. 

2.  To  get  the  dead  center,  place  a  fine  pointer  from  a  fixed  rest  close  to  the 
fly  wheel's  outer  rim  in  front.     Turn  fly  wheel  to  bring  the  crosshead  to  about 
£  inch  from  the  outer  end  of  its  travel.     Mark  accurately  the  guide  at  the  end 
of  crosshead  and  the  rim  opposite  the  pointer. 

Continue  the  turn  of  the  engine  until  the  same  end  of  crosshead  returns 
exactly  to  the  mark  on  the  guide.  Mark  the  pointer's  place  on  the  rim  and 
turn  the  wheel  so  that  the  pointer  stands  midway  of  the  two  marks  on  the 
rim.  The  engine  is  now  at  its  outer  dead  center.  A  fine  ^  straight  line  drawn 
on  the  guides  along  the  crosshead  end  marks  the  position.  Next  find  and 
mark  the  inner  dead  center. 

3.  To  line  up  an  engine  (horizontal)  is  to  find  if  cylinder's  axis  prolonged  inter- 
sects the  axis  of  the  main  shaft  at  right  angles,  and  the  axis  of  the  crosshead 
pin  in  all  positions,  and  if  the  main  shaft  is  level. 

Disconnect  and  remove  all  parts  from  crank  pin  to  and  including  back  cylin- 
der head.  To  any  bolt  of  this  head,  bolt  the  slotted  stick  across  the  head  to  hold 
one  end  of  the  fine  string  in  the  axis  of  the  cylinder.  Draw  the  string  taut 
through  the  cylinder  to  an  adjustable  upright  in  front  of  the  engine.  With 
inside  calipers  carefully  adjust  the  string  to  the  centers  of  the  two  counterbores. 
This  is  the  center  line  of  the  engine,  to  which  other  parts  are  adjusted. 

(a)  Put  one  leg  of  the  square  against  an  inner  crank  face  so  that  the  outer 
edge  of  the  other  leg  is  in  the  shaft's  axis     See  if  the  edge  just  touches  the  line 
as  the  crank  is  turned. 

(6)  To  square  the  shaft,  turn  the  crank  pin  forward  so  that  it  almost  touches 
the  center  line  of  the  cylinder.  Caliper  between  line  and  crank  or  disc.  Turn 
crank  pin  backward  to  line  and  likewise  caliper.  .If  the  two  distances  are  equal 
the  shaft  is  square.  If  not  square,  move  the  out-end  pillow  block. 

(c)  To  level  the  shaft,  apply  the  spirit  level  on  top  and  reverse  it.     Or,  better, 
drop  a  plumb-line  in  front  of  the  crank  face  and  caliper  at  the  up  and  down 
half  stroke  similarly  as  in  squaring.     If  the  shaft  is  out,  shift  it  by  liners,  babbitt, 
thicken  or  thinner  brasses,  or  by  using  a  file,  as  required. 

To  verify  both  the  level  of  shaft  and  trueness  of  fly  wheel,  drop  a  plumb  line 
from  the  ceiling  past  the  wheel's  outer  rim  and  center  and  turn  the  wheel. 

(d)  To  line  the  guides,  lay  a  straightedge  across  the  two  guides  and  caliper 
between  it  and  the  center  line  the  whole  length  of  the  guides.     Likewise  caliper 
between  line  and  the  inside  edges.     Measurements  will  show  if  center  line  inter- 
sects the  axis  of  the  crosshead  pin.     If  necessary,  dress  the  guides  with  file  or 
sandpaper,  or  insert  shims. 

(e)  To  verify  (b  and  d),^ey  UP tne  connecting  rod  snug  to  the  crank  pin,  and  while 
turning  the  crank  see  if  the  free  end  of  the  rod  moves  parallel  with  the  guides. 

4.  To  align  valve  rod  and  eccentric,  less  liable  to  derangement,  will  require 
like  expedients. 

5.  To  find  whether  cylinder  has  worn  out  of  true,  caliper  all  around  the  center 
line  in  one  circle,  then  another,  and  so  on  along  the  inside  of  the  cylinder. 

6.  To  test  the  fit  of  the  piston:  (a)  Loosen  the  connecting-rod  keys,  and,  by 
turning  the  fly  wheel,  bring  the  piston  to  the  head  end.     Take  off  cover,  also 
the  follower  on  the  piston,  and  see  that  the  piston  rings  press  against  the  cylin- 
der bore  all  around  without  binding. 

(b)  For  a  check,  put  the  engine  to  the  other  dead  center  and  admit  a  little 
steam.     Leaking,  if  any,  can  be  seen  at  the  open  end. 

(c)  Or,  without  removing  the  head  end,  if  the  cylinder  is  piped  for  indicator, 
relief  valve,  or  exhaust  to  air,  turn  crank  to  either  dead  center  and  open  the 
cock  at  the  end  opposite  from  that  at  which  steam  is  very  slowly  admitted. 
Steam  will  appear  at  the  cock  if  the  piston  leaks. 

(d)  The  split  of  a  piston  ring  is  down  in  a  horizontal  engine.     If  two  rings, 
they  break  joints  on  the  lower  half. 


HANDBOOK   FOK    ELECTRICIANS. 


THE    STEAM    ENGINE. 


25 


7.  The  crosshead. — It  in  essential  to  keep  the  piston  rod  exactly  in  the  center 
line.     Give  the  gibs  an  easy  sliding  fit  without  lost  motion.     Ease  away  on  the 
crosshead  pin  inside  the  connecting  rod  to  prevent  undue  wear  (fig.  24). 

8.  To  get  the  true  length  of  connecting  rod:  (a)  Move  piston,  with  crosshead 
disconnected,  against  one  cylinder  head,  i.  e.,  the  striking  point,  and  mark  the 
guide  opposite  crosshead  end.     Do  the  same  for  the  other  head.     Suppose  the 
distance  between  both  guide  marks  =  25  inches ;  between  centers  of  crank  pin 
and  shaft  =  12  inches.     Then  full  stroke  =  24  inches,  and  clearance  at  either 
end  =  i  inch.     Now  move  crosshead  £  inch   back  from  the  striking  point 
mark,  bring  crank  to  dead  center,  and  with  a  tram  measure  between  the  outside 
centers  of  crank  pin  and  wrist  pin  for  the  required  length. 

(6)  To  lengthen  the  rod  insert  liners  between  its  brasses  and  stud  ends. 

(c)  To  put  on  the  rod  move  the  piston  slightly  toward  the  crank  and  adjust 
the  keys  so  that  the  bores  of  the  brasses  easily  fit  without  play. 

(d)  To  take  up  lost  motion  loosen  the  set  screws,  drive  down  the  key,  and 
tighten  the  set  screws.     It  is  a  good  plan  to  drive  in  the  key  until  the  brasses 
bind,  mark  the  key  and  slide  it  back  to  a  proper  fit,  marking  it  again  for  later 
adjustment,  if  necessary. 

(e)  To  equalize  clearance,  usually  i  to  t  inch,  in  the  cylinder,  lengthen  or 
shorten  the  connecting  rod. 

9.  To  adjust  main  shaft  bearings,  the  shaft  is  shifted  on  either  side,  or  both, 
by  the  use  of  thicker  or  thinner  shims,  babbitt  or  brasses.     If  the  brasses  meet, 
tighten  the  nuts  to  an  easy  bearing.     If  not,  lay  in  a  sufficiently  thick  wire  of 
lead  to  take  the  compression  and  screw  the  nuts  to  a  bearing.     Then  replace  by 
a  shim  gauged  to  the  same  thickness  and  screw  the  nuts  home. 

If  the  lead  wire  is  thicker  at  one  end,  the  shim  will  be  made  the  same. 

10.  To  set  a  common  slide  valve,  is  to  make  the  leads  at  both  ports  equal,  and 
the  full-port  openings  as  nearly  equal  as  possible.     Leads  are  made  equal  or 
unequal  by  changing  valve  or  eccentric  rod's  length ;  but  if  both  leads  are  equal, 
change  of  amount  is  gotten  by  changing  the  angle  of  advance.     Always  com- 
pare the  openings  by  inserting  a  long,  thin  wedge. 


23.  Annington  &  Sims  D.  C.  Set. 

(a)  Take  off  the  steam-chest  cover  (fig.  23),  give  all  connections  a  close  working 
fit,  place  crank  at  either  dead  center,  and  measure  the  lead  for  each  port ;  if  the 
leads  are  equal  to  each  other  and  to  the  amount  given  by  the  builder,  the  valve 
is  properly  set.  If  not,  change  the  valve  rod's  length  by  the  half  difference,  and 
repeat  the  operation,  which  will  probably  first  require  a  change  of  the  eccentric's 
position  to  bring  the  lead  right  at  the  first  dead  center. 

Suppose  the  valve  has  proper  lead,  Jv  inch  with  crank  at  first  dead  center,  and 
shows  a  lap  of  f  inch  at  the  other  port  with  crank  at  second  dead  center,  the 


HANDBOOK   FOR   ELECTRICIANS. 


THE   STEAM   ENGINE. 


27 


valve  rod's  length  is  then  changed  by  ^  inch.  Now  put  crank  at  first  dead 
center  and  change  eccentric's  position  to  give  y^-inch  lead  and  move  crank 
(always  in  its  working  direction)  to  second  dead  center,  and  so  on. 

(5)  If  the  valve  is  controlled  by  a  wheel  governor,  block  the  weights  out  to 
their  positions  at  normal  speed  and  proceed  as  above.  Both  length  of  rod  and 
angle  of  advance  are  successively  changed  in  setting  valves. 

(c)  In  vertical  engines  with  cylinder  above,  the  lead  at  the  crank-end  port  is 
given  slightly  increased  lead  over  the  upper  to  compensate  for  weight  of  moving 
parts  and  the  wear  downwards. 


(J)  TO  PACK  THE  PISTOX  ROD. 

(1)  Cut  the  rubber  or  other  material  into  four  or  more  rings  of  square  cross 
section  with  beveled  split  to  fit  rod  and  box  so  closely  that  the  finger  can  push 
them  into  place.     The  first  split  is  up  ;  the  others,  break  joints.     Rub  graphite 
or  chalk  on  the  outside  to  prevent  its  sticking  to  the  iron. 

Screw  down  the  gland  evenly,  first  one  nut  a  partial  turn  and  then  the  other 
a  little  more,  and  so  on  alternately. 

(2)  To  stop  a  leak,  tighten  little  at  a  time.     If  several  trials  fail,  reverse  the 
packing,  or,  better,  renew  with  soft  packing  always  kept  in  stock. 

(3)  The  troubles  with  packing  result  from  ill-fitting  rings,  engine  out  of  line, 
rough  rods,  not  correcting  the  first  small  leak,  too  long  or  too  short  or  too  few 
rings,  or  too  small  stuffing  box.     The  valve  rod  is  similarly  packed. 

(K)    THE    PISTOX  VALVE  IX  COMMON  TJSE   IS 
BALANCED. 

This  valve  is  cylindrical  and  usually  hollow.  Steam  passes  over  its  edges  on 
all  sides  and  does  not  force  the  valve  against  its  seat  with  unnatural  pressure 
as  in  the  case  of  the  D-slide  valve.  Its  action  is  precisely  the  same  and  the  fore- 
going principles  apply,  whether  the  piston  valve  admits  steam  at  the  ends  of  the 
chest  and  exhausts  at  the  middle,  or  admits  steam  from  the  middle  around  the 
valve  and  exhausts  at  its  ends. 


24a.   The  Cylinder  and  Valve. 

To  the  latter  class  belongs  the  valve  (fig.  24a)  of  the  Armington  &  Sims 
engine,  shown  in  the  lead  position.  Live  steam  surrounds  the  valve  and 
fills  its  interior  through  one  or  the  other  of  its  end  openings.  Steam  has 
already  started  into  the  head-end  port  from  the  middle  of  the  chest  and  from 
the  interior  of  the  valve  by  way  of  the  right-hand  opening.  The  exhaust 
occurs  quickly  at  either  end  of  the  cylinder  through  direct  passages.  The  valve 
carries  check  rings  at  both  ends. 

The  Rites  governor  (fig.  246)  is  extremely  simple,  sensitive  and  powerful. 
The  eccentric  arm  at  its  greatest  elongation  is  short,  so  that  the  valve's  travel 
is  small.  The  cut  explains  better  than  words  its  mode  of  operation. 


HANDBOOK    FOR    ELECTRICIANS. 


24b.  A.  and  S.  Governor. 

The  main  journals  have  chain  continuous  oilers ;  the  crank  pin,  a  centrifugal 
oiling  device ;  and  the  crosshead  runs  in  oil,  all  supplied  from  a  central  reservoir. 
There  is  no  throwing  of  oil. 

Fig.  22a  shows  the  new  Arrnington  &  Sims  wheel  governor  and  its  con- 
nection with  the  valve. 


24c.  End  View  Oiling  Device. 


III.— THE  HORNSBY-AKROYD  OIL  ENGINE 


Has  no  ignition  apparatus  and  is,  when  properly  attended,  reliable.  One 
pint  kerosene  maintains  one  horsepower  for  one  hour. 

(A)  THE  ENGINE. 

1.  The  engine  (fig.  26)  is  four  cycle,  i.  e.,  in  its  propulsion  four  different 
operations  occur  behind  the  piston  in  the  four  strokes  which  cause  two  complete 
turns  of  the  pulley.  They  are — 

First  stroke. — Admission  (or  suction).  During  the  first  outward  stroke  air  is 
drawn  into  the  cylinder  and  a  thin,  momentary  jet  of  kerosene  oil  ic  sprayed 
into  the  adjoining  hot  combustion  chamber  or  vaporizer  (fig.  26a) . 

Second  stroke. — Compression.  In  the  following  inward  stroke  the  air  is  driven 
through  the  narrow  neck  into  the  vaporizer  to  form  with  the  oil  vapor  a  mixture 
which  at  the  end  of  the  stroke  is  ignited  by  the  heat  in  the  chamber. 


26.  Beau  de  Rochas  Cycle  of  H.=A.  and  most  Explosive  Engines. 

Third  stroke. — Explosion  plus  expansion  of  the  gas  through  the  neck  into  the 
chamber  then  drives  the  piston  outward  with  a  maximum  pressure  of  130 
pounds  per  square  inch  and  a  mean  of  40  to  75  pounds. 


26a. 

Fourth  stroke. — Exhaust  of  the  products  of  combustion  from  the  cylinder  into 
the  exhaust  chamber  and  pipe  occurs  during  the  next  inward  stroke,  or  final 
cycle. 

During  the  first  outstroke  the  thin  stream  of  oil  is  instantly  vaporized  on 
striking  the  heated  interior  surface  of  the  vaporizer,  and  the  proper  amount  of 

(29) 


30 


HANDBOOK   FOR   ELECTRICIANS. 


THE   HORNSBY-AKROYD   OIL   ENGINE. 


31 


air  heated  en  route  by  the  hot  exhaust  chamber,  is  drawn  into  the  cylinder. 
Mixture  and  compression  follow  on  the  following  instroke,  at  the  end  of  which 
ignition  is  caused  by  the  heating  effects  of  compression,  friction,  and  vaporizers 
combined.  The  impulse  is  given  only  during  one  stroke  in  four.  The  vapor- 
izer is  protected  from  cooling  air  currents  by  the  hood,  and  its  heating  is  con- 
trolled by  the  damper  on  top.  Cylinder  and  valve  box  are  cooled  by  a  water 
jacket. 
2.  Number  and  names  of  parts : 


1.  Cylinder  liner.  30. 

•_'.  Cylinder  casing.  31. 

3.  Vaporizer.  32. 

4.  Vaporizer  cap.  33. 

5.  Vaporizer-cap  joint  ring.  34. 
t'i.   Vaporizer  cover.  35. 
7.  Vaporizer-cover  lid.  36. 
S.  Vaporizer-cover  filling  piece.        37. 
9.  Valve-box  journal.  38. 

10.  Valve-box  sleeve.  39. 

11.  Spray  no/.zle.  40. 

12.  Horizontal  valve.  41. 

13.  Horizontal-valve  spring.  42. 

14.  Vertical  valve.  43. 

15.  Vertical-valve  spring.  44. 

16.  Valve  box.  45. 

17.  Valve-box  screw  cap.  46. 

18.  Valve-box  coupling.  47. 
I: i.  overflow  glass.  48. 

20.  Half  union.  49. 

21.  Oil-pump  can.  50. 

22.  Oil-pump  plug.  51. 

23.  Oil-pump  plunger.  52. 

24.  Oil-pump  plunger  spring.  53. 

25.  Oil-pump  plunger  lock  nut.  54. 

26.  Oil-pump  plunger  head.  55. 

27.  Oil-pump  plunger-bead  guide.      56. 

28.  Oil-pump  gauge.  57. 

29.  Oil-pump  body. 


Oil-pump  gland.  58. 

Bed  plate.  59. 

Bearing  cup.  60. 

Splasher.  61. 

Oil  tank.  62. 

Oil  filter.  63. 

Filter  cock.  64. 

Worm  gear.  65. 

Gear  wheel.  66. 

Gear  guard.  67. 

Crank  .shaft.  68. 

Crank-pin  oiler.  69. 

Oiler  elbow.  70. 

Piston.  71. 

Piston  rings.  72. 

Wrist  pin.  73. 

Connecting  rod.  74. 

Connecting-rod  head  end.  75. 

Connecting-rod  crank  end.  76. 

Compression  plates.  77. 

Cam  shaft.  78. 

Governor  wheel.  79. 

Governor  pinion.  80. 

Governor-gear  guard.  81. 

Governor  bracket.  82. 

Governor  spindle.  83. 

Governor  counterpoise.  84. 
Governor-counterpoise  lever;        85. 


Governor  balls. 
Governor  counterweight. 
Governor-counterweight  lever. 
Governor-regulating  plate. 
Governor  fork. 
Governor-fork  spindle. 
Governor  connecting  rod. 
Governor  connecting-rod  lever. 
Valve  lever. 
Air-valve  cam. 
Exhaust-valve  cam. 
Cam  rollers. 
Lever  fulcrum. 
Lever-fulcrum  pin. 
Air-valve  lever. 
Exhaust-valve  lever. 
Cam  shifter. 
Locking  handle. 
Air-exhaust  valve  box. 
Air-exhaust  valve-box  cover. 
Air-exhaust  valve  spring. 
Air  valve. 
Exhaust  valve. 
Cylinder  lubricator. 
Cylinder-lubricator  cover. 
Cylinder-lubricator  pulley. 
Fly  wheel. 
Fly-wheel  key  guard. 


27 a.  Cylinder  End  Projection. 


HANDBOOK    FOR   ELECTRICIANS. 


THE    HOKN.SBY-AKROYD    OIL   ENGINE. 


33 


1714—3 


34 


HANDBOOK   FOR    ELECTRICIANS. 


3.  The  oil  pump  (fig.  28),  actuated  by  the  same  lever  as  the  air-inlet  valve 
(fig.  30),  performs  the  double  office  of  suction  on  the  upstroke  and  of  forcing  on 
the  downstroke.     The  suction  as  well  as  the  forcing  side  has  two  check  valves 
in  series  for  certainty  of  action.     On  the  downstroke  oil  is  forced  direct  to  the 
valve  box. 

4.  Valve  box  (fig.  29). — Here  are  two  valves,  the  "horizontal"  or  check  valve 
for  keeping  the  oil  from  flowing  back  and  preventing  the  possibility  of  prema- 
ture explosion,  and  the  "vertical"  or  by -pass  valve  for  regulation. 


WATER  IIUET 


E  RT.  VALVC 


28.  Oil  Pump. 


It  OVERFLOW 
TO    TANK 


HOR. VALVE 
29.  Check  and  By=Pass  Valve  Box. 


5.  The  regulation  of  the  engine  is  effected  by  altering  the  supply  of  oil  in  two 
ways:  first,  by  changing  the  length  of  stroke  of  the  pump,  i.  e.,  the  oil  supply, 
and,  second,  automatically  by  a  sensitive  ball  governor  which  opens  the  by-pass 
valve  in  the  valve  box,  and  deflects  a  portion  or  all  of  the  oil  jet  from  the  vapor- 
izer through  the  overflow  outlet  back  to  the  tank.     During  the  piston's  first  or 
suction  stroke  the  pump  injects  the  oil  (opening  the  "horizontal  valve " )  through 
the  spray  nipples  (see  "oil  jet,"  fig.  29)  into  the  vaporizer ;  but  if  the  by-pass  valve 
is  partially  or  wholly  depressed  at  this  time,  part  or  all  of  the  oil  will  overflow. 

6.  The  air-inlet  and  the  exhaust-poppet  valves  (fig.  30)  close  at  the  proper 
times  the  exhaust  chamber  to  their  respective  pipes.     Always  under  the  tension 


30.  Exhaust-Chamber  Side  of  Engine. 


THE    HORNSBY-AKROYD    OIL    ENGINE. 


35 


of  springs  they  are  actuated  by  levers  moved  by  cams  on  the  auxiliary  shaft. 
Through  the  port  (marked  in  the  figure)  leading  from  the  exhaust  chamber  to  the 
rear  interior  of  the  cylinder,  the  air  passes  on 
its  way  in  and  the  exhaust  products  on  their 
way  out. 

8.  Fig.  30or  gives  the  crank  positions  at  the 
instants  when  the  poppet  valves  open  and  close. 
The  air  valve  closes  just  after  the  crank  has 
passed  out-center.     The  exhaust  valve  opens  at 
about  85  per  cent  of  full  stroke  and  closes  just 
after  the  air  valve  has  opened. 

9.  The  piston  (fig.  276)  should  make  a  good 
fit  top  and  bottom,  and  not  rub  hard  on  the 
sides,  as  ascertained  by  inspection  and  turning 
the  fly  wheel.     The  three  or  five  rings  break- 
ing joints  on  the  underside  must  not  leak.  Their 
close  fit  and  the  good  lubrication  of  the  piston 
are  absolutely  essential.     Mechanical  or  sight 
feed  lubricator  is  always  used. 

(B)  ENGINE-ROOM  INSTRUCTIONS. 

STARTING. 

1.  Before  starting  see  that  oil  and  water  tanks  (fig.  31)  are  full,  and  that  the 
three  cocks  which  supply  water  to  the  water  jackets  are  fully  open. 

2.  Heating  the  vaporizer.— Y\\\  the  lamp  with  oil  outside  of  the  engine  room, 
to  avoid  smoke,  and  put  a  piece  of  wick  into  the  cups  which  are  formed  round 
the  pipes.    These  wicks  which  should  consist  of  a  piece  of  ordinary  asbestos 
packing,  will  last  for  several  weeks. 


30a. 


WATER 

COOLING 

TANK 


31.  Water-Cooling  Connections. 

A  little  kerosene  should  then  be  poured  into  the  cup  under  the  coil  and  lighted. 
When  this  is  nearly  burnt  out,  pump  up  the  reservoir  with  air  by  the  air  pump, 
when  oil  vapor  will  issue  from  the  small  nozzle  and  give  a  clear  flame.  Then 
place  the  lamp  on  the  stand  so  that  the  coil  is  one-half  inch  from  the  vaporizer. 
Turn  the  damper  for  draft. 

When  it  is  required  to  stop  the  lamp,  turn  the  little  thumbscrew  on  the  reser- 
voir-filling nozzle,  and  let  the  air  out.  Should  at  any  time  the  nozzle,  where 


36 


HANDBOOK   FOR   ELECTRICIANS. 


the  vapor  comes  out,  get  choked  up,  it  can  be  cleaned  with  the  small  prickers 
which  are  sent  for  that  purpose. 

The  heating  up  of  the  vaporizer  is  one  of  the  most  important  things  to  be 
attended  to,  and  care  must  be  taken  that  it  is  made  hot  enough  at  starting. 
The  attendant  must  see  that  the  lamp  is  burning  properly,  and  that  a  good  clear 
flame  is  given  off  from  five  to  ten  minutes  according  to  the  size  of  the  engine. 
If,  however,  the  lamp  is  burning  badly,  it  may  take  longer  to  get  up  the  proper 
heat.  It  is  most  important  that  this  should  be  carefully  attended  to,  as,  though 
the  engine  may  start  if  the  vaporizer  is  not  as  hot  as  it  ought  to  be,  the  engine 
will  run  badly,  and  perhaps  soon  stop  altogether.  Failure  to  get  engines  to  run 
properly  can  in  most  cases  be  traced  to  the  above. 

If  the  vaporizer  is  partly  jacketed,  close  the  valve  on  the  inlet  water  pipe 
before  heating  up,  and  open  or  partially  open  while  running. 

3.  Oiling. — See  that  the  oil  cups  on  the  two  main  crank-shaft  bearings  are  fitted 
with  proper  wicks  and  filled  with  oil.  Adjust  the  lubricator  of  the  large  end 
of  the  connecting  rod  and  oil  the  small  one  which  is  inside — also  the  bearings 
on  horizontal  shaft  and  the  skew  gearing — the  rollers  at  the  ends  of  the 

valve  levers  and  their  pins,  and  the  pins  on  which 

rn the  levers  rock — the  governor  spindle  and  joints, 

i«=^kni~  \         the  bevel  wheels  which  drive  same,  and  the  joints 

(f  OJ  /         that  connect  the  governor  to  the  small  relief  valve 

f*^  \       on  the  vaporizer — twenty  places  in  all.     For  such 

bearings  none  but  the  best  engine  oil  should  be 
used.  Oiling  should  always  be  done  during  heating 
up  the  vaporizer,  and  the  lamp  should  be  left  burn- 
ing for  a  few  minutes  after  starting. 

4.  To  start. — Turn  the  small  regulator  on  the 
governor  bracket  (fig.  276)  to  position  "Shut,"  and 
work  the  pump  lever  up  and  down  until  oil  is  seen 
to  freely  pass  the  overflow  glass.  Then  turn  the 
small  regulator  to  position  "Open,"  work  the  pump 
lever  up  and  down  again  one  or  two  strokes,  then 
give  the  fly  wheel  one  or  two  smart  turns,  when 
the  engine  will  start  readily.  The  engine  will 
often  start  better  by  first  turning  the  fly  wheel  the 
reverse  way,  when  an  explosion  will  sometimes  be 
obtained  which  will  start  the  engine,  and  in  any 
case  the  rebound  thus  obtained  from  the  com- 
pressed air  will  help  the  fly  wheel  to  be  turned  forward  more  easily. 

The  handle  upon  the  cam  shaft,  before  starting  engine,  must  be  placed  in  the 
position  marked  "To start, "in  order  to  relieve  a  part  of  the  "compression," 
and  immediately  the  engine  has  got  up  sufficient  speed  to  affect  the  four  cycles 
this  handle  should  be  placed  in  position  marked  "  To  work." 

No  time  should  be  lost  in  starting  the  engine  after  the  vaporizer  has  been 
sufficiently  heated,  as  the  engine  will  not  run  satisfactorily  if  the  vaporizer  is 
allowed  to  cool  down  after  heating  it.  If  too  much  oil  is  pumped  into  vaporizer 
it  will  be  difficult  to  start  up. 

Starting  gear  is  not  necessarily  required  except  for  the  larger  engines,  say 
35-horsepower  and  upwards ;  35-horsepower  engines  can,  however,  be  started  by 
two  men.  Release  the  air  from  the  lamp  directly  the  engine  starts. 

In  turning  over  the  fly  wheel  there  is  a  certain  knack  by  which  a  skillful 
engineer  exerts  his  force  only  once  or  twice,  and  usually  on  a  certain  one  of  the 
spokes ;  it  is  the  one  which  he  reaches  by  stooping  down  to  effect  the  compres- 
sion. If  the  engine  starts  in  the  wrong  direction  it  will  generally  reverse  itself 
after  a  few  turns,  when  give  it  assistance.  To  avoid  accident,  never  put  a  foot 
or  a  leg  on  a  spoke  to  assist  in  starting. 

5.  Failure  to  start  is  generally  due  to  vaporizer  not  being  hot  enough  (barely 
perceptible  red  in  the  dark).  If  the  oil  tank  is  full,  if  piston  is  clean,  and  if 
reheating  the  vaporizer  again  fails,  examine  the  engine : 

(a)  Oil  pump.—  Turn  the  regulator  to  "Shut"  and  work  the  pump  by  hand  as 
in  starting  to  see  if  a  full  stream  of  oil  free  from  air,  passes  the  glass  as  it 
should  do. 

(6)  If  the  stream  is  not  a  full  one,  open  the  three-way  cock  from  oil  reservoir; 
if  oil  flows  out  freely  the  filter  is  in  order.  If  not,  clean  it. 

(c)  If  the  pump  is  still  unsatisfactory,  see  if  air  is  in  the  pump  or  pipes  by 
disconnecting  the  oil-supply  pipe  from  the  vaporizer  valve  box,  pumping  until 
oil  overflows,  then  pressing  left  thumb  tightly  over  outlet,  pump  down  once 
quickly.  If  the  pump  plunger  yields,  air  is  in  the  pipes.  Or,  pump  several  times 


THE    HORNSBY-AKROYD    OIL    ENGINE. 


37 


quickly  and  then  remove  the  thumb  suddenly ;  if  air  is  in  the  pipes,  its  elastic 
force  will  cause  a  long  jet  (fig.  32a). 

(d)  If  there  is  no  air  in  the  pipes,  inspect  the  action  of  the  valves  by  pressing 
the  pump  steadily  down  while  closing  the  outlet  with  the  thumb.     If  the  plunger 
yields  under  a  steady  pressure  but  not  under  a  sudden  jerk,  the  suction  valves 
are  not  tight.    To  stop  leakage,  wash  out  valve 

boxes  with  oil ;  if  this  fails,  tap  the  steel  ball 
valves  on  their  seats  with  a  copper  punch. 

(e)  To  examine  the  vaporizer  valve  box, 
take  it  off,  reconnect  it  with  its  pipe,  stroke 
the  pump  as  in  regular  working  and  observe 
the  jet.     If  the  jet  is  full,  positive  and  clear, 
and  begins  with  the  downstroke   and  does 
not  dribble  after  the  the  end  of  it,  the  jet  is 
normal — a  very  important  condition.     Watch 
the  effect  of  partially  and  wholly  depressing 
the  vertical  valve  while  pumping. 

RUNNING. 


32a.  Pump  Detached. 


(a)  Good  action  requires  three  things — 

(1)  Oil  and  air  delivered  to  vaporizer  in 
right  amounts  at  the  right  time. 

(2)  Sufficient  compression  of  the  mixture  before  ignition. 

(3)  Ignition  of  gas  complete  at  the  proper  time. 

(5)  Regulation. — (1)  When  the  engine  is  working  at  its  full  power,  the  dis- 
tance between  the  two  round  flanges  on  the  pump  plunger  (fig.  28)  should  be 
such  that  the  hand  gauge  will  allow  the  part  stamped  "  1 "  to  just  fit  in  between 
the  flanges ;  and  if  at  any  time  the  positions  of  these  flanges  be  altered,  they  can 
always  be  readjusted  to  this  gauge.  The  other  lengths  on  the  hand  gauge  are 
useful  for  adjusting  the  pump  to  economize  oil  when  running  on  a  medium 
load  "2"  or  a  light  load  "3"  of  the  gauge.  Still,  familiarity  with  an  engine  is 
better  than  the  gauge  for  regulation.  If  overflows  show  of tener  than  once  in 
5  or  6  strokes,  the  pump  stroke  may  be  shortened. 


32b.  Governor  With  Overflow  Glass. 

(2)  The  governor  (fig.  326)  is  adjusted  to  reduce  the  oil  let  occasionally.  At 
normal  speed  it  revolves  about  i  inch  clear  of  its  seat.  When  it  runs  too  fast 
its  connecting  mechanism  depresses  the  vertical  valve  and  diverts  more  or  less 
oil  to  the  overflow.  Moving  the  weight  out  from  the  fulcrum  slows  the  gov- 
ernor's action.  "  Governor  hunting, "  causing  the  engine  to  run  unsteadily,  is 
due  to  joints  or  spindle  becoming  bent,  dirty  or  sticky. 

When  engines  are  required  to  run  empty  or  light,  it  is  best  to  alter  the  stroke 
of  the  pump  to  just  the  amount  of  oil  that  will  keep  the  engine  running,  and 
can  even  be  reduced  so  that  the  speed  of  the  engine  is  a  few  revolutions  under 
the  usual  speed  (so  that  the  governor  can  not  cut  out  any  oil,  which  allows  the 
vaporizer  to  get  a  small  charge  of  oil  each  time),  and  thus  keep  it  from  getting 
cooled  down.  Also  the  cock  on  the  return  or  lower  water  circulating  pipe  and 


38 


HANDBOOK   FOR   ELECTRICIANS. 


32c. 


the  cylinder  jacket  can  be  nearly  closed,  so  as  to  keep  the  cylinder  warmer. 
The  above  remarks  do  not  apply  when  the  work  is  intermittent,  and  the  engine 
is  not  running  light  very  long  together. 

(c)  In  the  valve  box  (figs.  27b,  29),  if  the  horizontal  valve  is  not  working  prop- 
erly, vapor  from  explosion  will  be  found  passing  the  overflow  glass  whenever  the 
little  lever  or  the  finger  presses  down  the  vertical  valve.     Unscrew  the  cap  and 
turn  the  valve  by  its  tail  around  to  dislodge  any  dirt  in  the  seat  of  the  valve, 
and  see  that  the  spring  is  closing  the  valve.     If  this  does  not  stop  leaking,  take 
out  the  valve,  ground  it  on  its  seat  with  a  little  emery  flour  and  water,  and 
take  care  in  replacing  valve  and  sleeve  to  preserve  the  same  thickness  of  jointing 
material,  and  hence  same  valve  opening. 

(d)  The  spray  hole  or  holes  (figs.  276  and  29)  are  liable  to  get  clogged.     The 
valve  box  is  taken  off  and  each  hole  is  cleared  by  the  little  wires  supplied  for  the 
purpose,  so  as  not  to  increase  the  size. 

(e)  If  the  pipe  to  the  vaporizer  valve  box  does  not  rise  all  the  way  from  the 
pump,  or  if  it  gets  bent  down,  an  air  pocket  will  be  formed  in  which  air  will  be 
compressed  upon  each  stroke  of  the  pump,  and  thus  allow  the  oil  to  go  in  slowly 
and  not,  as  it  should  do,  suddenly.     Also  if  the  oil  tank  gets  emptied  of  oil  at 

any  time,  air  will  get  into  the  suction 
and  delivery  pipes  of  pump,  and  it  will 
take  some  time  before  the  oil  going  through 
the  pump  and  pipes  will  get  rid  of  this  air, 
so  that  for  a  while  the  engine  would  not 
work  properly,  as  the  air,  by  getting  com- 
pressed as  the  pump  works,  will  interfere 
with  the  oil  being  pumped  in  suddenly,  as 
it  should  be.  It  is  best,  if  ever  the  oil  gets 
below  the  filter  in  the  tank,  to  work  the 
pump  by  hand  for  say  ten  minutes,  hold- 
ing open  the  relief  valve  on  the  vaporizer 
valve  box  so  as  to  get  air  well  out  of  the 
pipes.  Derangement  of  the  pump  rarely 
occurs.  If  the  packing  is  renewed  it  should  not  be  screwed  so  tight  as  to  bind 
the  plunger. 

(/ )  The  air  inlet  and  exhaust  poppet  valves  (fig.  32c)  must  always  work  freely 
and  definitely  and  drop  on  to  their  seats.  They  can  at  any  time,  if  required,  be 
made  tight  by  grinding  in  with  a  little  flour  of  emery  and  water.  The  set  screws 
(fig.  32d)  at  the  ends  of  the  levers  that  open  these  valves  must  not  be  screwed  up 
so  high  that  the  valves  can  not  close ;  this  can  always  be  ascertained  by  seeing 
that  the  rollers  at  the  other  end  of  the  levers  are  just  clear  of  the  cams,  that  is, 
when  the  projecting  part  of  the  cams  is  not  touching  them. 

(gr)  Cylinder's  proper  temperature  lies  between  110°  and  130°  F.  The  cooling 
tank  is  kept  full  of  fresh  water  below  120°  F.  If  the  temperature  tends  to  rise 
above  this,  cold  water  must  be  added,  or  a 
pump  capable  of  delivering  10  gallons  per  hour 
per  horsepower  of  engine  is  connected  with 
the  shaft  to  maintain  from  another  source  cir- 
culation around  the  cylinder.  If  a  cheap  sup- 
ply under  pressure  is  available,  use  it.  If  the 
supply  is  above  70°  F.,  as  at  many  southern 
posts,  much  more  water  will  be  necessary. 
Sea  water,  if  unavoidable  and  if  circulated 
rapidly,  can  be  used,  but  the  water  jacket 
should  be  watched  for  deposits. 

(h)  If  the  piston  gets  black  and  gummy,  or 
the  exhaust  gases  are  like  smoke;  or  "cough- 
ing "  is  continuous,  combustion  is  incomplete,  due  chiefly  to  excess  of  oil  or  too 
little  air,  or  possibly  to  leakage  over  the  piston  rings. 

(i)  Ignition  can  be  retarded  by  lessening  the  vaporizer's  heat  and  slightly 
reducing  compression  by  increasing  the  clearance  in  the  cylinder.  In  starting 
or  on  light  loads  the  water  inlet  to  valve  box  may  be  partly  or  wholly  closed  to 
preserve  the  vaporizer's  temperature. 

(j)  Heat  in  exhaust  and  vaporizer  valve  boxes  sometimes  causes  the  valves 
not  to  seat  or  their  stems  to  stick,  and  necessitates  regrounding. 

(k)  If  a  little  oil  is  sent  into  the  heated  vaporizer  and  the  fly  wheel  is  turned 
forward,  the  engine  should  start  freely.  If  not,  test  the  spray  by  hand  and  turn 
the  fly  wheel  backward  to  test  the  compression.  If  this  pressure  is  so  slight 


32d. 


THE    HORNSBY-AKROYD    OIL   ENGINE. 


39 


(the  relief  cam  being  out  of  action)  that  it  can  be  overcome  by  hand,  there  is 
leakage  in  the  piston  rings,  the  air  or  exhaust  valve  or  some  joint  or  gasket. 

(/)  Watch  the  temperatures  and  oiling  of  bearings,  especially  of  the  cylinder ; 
use  just  enough  oil  for  the  load  and  listen  for  regular  action  after  fifteen  min- 
utes' run ;  keep  every  part  clean. 

(w)  For  subsequent  reference  in  time  of  trouble,  mark  on  the  gearing  or  record 
when  engine  runs  well,  the  exact  positions  of  crank  when  the  poppet  valves  open 
and  close  and  for  load  and  half  load,  or  the  usual  load  after  an  hour's  satisfac- 
tory run,  the  motion  of  pump  stroke,  heat  of  outlet  water,  frequency  of  oil  over- 
flow, governor's  rise,  vaporizer's  color  in  the  dark,  appearance  of  exhaust  and 
piston. 

(n)  The  engine  is  working  efficiently  if,  after  getting  warmed  up,  it  runs  on 
its  load  smoothly  to  the  eye  and  ear,  if  the  piston  shows  no  carbon  deposit,  if 
the  exhaust  gases  are  invisible  or  nearly  so,  and  if  the  explosions  sound  regu- 
larly, except  occasionally  when  the  governor  reduces  the  explosive  charge. 


33. 

STOPPING. 

(a)  Turn  the  small  regulator  on  the  governor  bracket  to  position  marked 
"Shut."    To  stop  quickly,  hold  down  the  air-valve  lever  at  the  same  time. 
If  the  engine  does  not  then  stop  readily,  the  spring  of  the  horizontal  check 
valve  is  weak  and  oil  is  entering  the  vaporizer  instead  of  all  coming  through 
the  overflow  valve,  as  it  should  at  "Shut."    If  the  stop  is  for  a  brief  period,  but 
more  than  five  minutes,  it  will  be  necessary  to  start  the  lamp  under  the  vaporizer. 

(b)  In  frosty  weather  do  not  omit, 
before  leaving  the  engine,   to  run  all 
water  out  of  the  pipes  and  water  jackets 
by  first  closing  the  main  water-pipe  cock 
and  opening  the  floor  cock.     The  small 
water  cocks  to  the  valve-box  water  jacket 
are  usually  left  open. 

Fundamental  Alterations. —  (a)  If 
air  or  exhaust  valves  appear  to  be  open- 
ing or  closing  at  the  wrong  time,  take 
off  the  nut  on  the  end  of  the  lay  shaft 
which  holds  the  skew  when  on,  and  see 
that  the  chisel  cuts  on  the  shaft  and  on 
the  skew  wheel  are  opposite  to  one  an- 
other, as  shown  in  fig.  33.  The  lay 
shaft  is  coned  where  the  skew  wheel  is 
fixed,  and  is  held  on  simply  by  fric- 
tion, the  nut  being  tightened  against  it. 

Should  it  at  any  time  be  necessary  to 
take  out  the  crank  shaft,  always  be  sure 
that  the  skew  wheel  gearing  is  put 
together  so  that  the  tooth  marked  p  33a.  ^it  Pulls  on  Lower  Run. 

on  the  crank-shaft  skew  wheel  fits  111 

between  the  two  teeth  inarked  O  on  the  lay-shaft  skew  wheel,  as  shown  on  the 
sketch  (fig.  33). 

(b)  To  reverse  the  direction  of  rotation,  exchange  the  relative  positions  of  the 
cams  actuating  the  air  and  exhaust  valves  and  the  fuel  supply. 


40 


HANDBOOK   FOR   ELECTRICIANS. 


THE    HORNSBY-AKROYD    OIL    ENGINE. 


41 


Fig.  33a  gives  also  the  positions  of  the  crank  at  the  moments  when  the  air  and 
exhaust  valves  open  and  close. 

The  pressure  in  the  cylinder  during  four  consecutive  strokes  and  the  impor- 
tant action  of  valves  and  other  parts  and  the  time  of  ignition  during  a  run, 
can  best  be  seen  by  means  of  cards  taken  with 
the  Crosby  or  other  indicator  (fig.  34).  If  these 
show  faults,  adjustments  may  be  made  to  correct 
them.  Unless  the  indicator  is  properly  set,  its 
drawing  will  be  misleading.  The  cut  shows  its 
attachment  to  the  engine  and  the  means  for  get- 
ting the  brake  horsepower  and  the  amount  of  oil 
consumed. 

All  cylinders  are  tapped  for  indicator  tests. 
The  operation  is  similar  to  that  for  steam  engines 
and  the  importance  of  getting  a  correct  card  is 
even  more  important. 

In  the  A  card  ignition  took  place  slightly  before 
the  piston  reached  the  end  of  its  stroke,  and  the 
pressure  during  the  first  third  of  the  expansion 
stroke  fell  off  tqo  rapidly.  The  exhaust  was  not 
free  and  the  compression  was  too  great. 

Diagram  B  shows  good  action  on  a  load.  The 
ignition  line  should  be  nearly  perpendicular  to  the 
atmospheric.  The  exhaust  opened  at  90  per  cent 
of  the  full  stroke,  and  the  pressure  during  exhaust 
and  suction  was  0.  There  is  good  area  between 
the  expansion  and  compression  lines,  and  all  lines 
show  steadiness. 

In  the  third  card  C  the  suction  line  below  the 
atmosphere  indicates  that  the  inlet  of  air  was 
hindered.  The  low  compression  line  points  to 
leakage  past  the  poppet  valves,  oil  inlet,  or 
piston.  From  the  waving  in  the  lines  and  short- 
ness of  figure,  the  indicator  may  not  be  in  proper 
order. 

In  the  D  card  the  events  are  lettered  in  the 
order  of  occurrence.  The  exhaust  was  choked, 
and  ignition  took  place  too  early.  Compression  D 

began  top  soon  and  became  too  great. 

Full  directions  for  erecting,  testing,  installing,  running,  and  repairing  this 
remarkable  engine  will  be  found  in  G-oldingham's  "Oil  Engines,"  from  which 
the  above  cuts  are  taken. 


IV.— THE  DYNAMO. 


(A)  GE:N~ERA:L  PRINCIPLES. 

The  short  exploring  magnetic  needle  will  show  that  the  space,  or  field,  between 
the  poles  of  a  horseshoe  magnet  has  the  strongest  magnetic  force  and  that  the 
imaginary  lii:es  therein  which  represent  the  direction  and  intensity  of  the  force, 
are  approximately  straight,  parallel  and  uniformly  distributed  (fig.  35). 

I.  Laws  of  the  induction  of  an  electromotive  force  in  a  loop  are  as  follows : 

1.  Induction. — An  E.  M.  F.  is  induced  or  generated  in  a 
coil  whenever  the  number  of  lines  of  magnetic  force 
through  it  is  changing — either  increasing  or  decreasing — 
by  the  motion  of  the  coil  or  lines,  or  both. 

2.  Direction. — Its  direction  is  clockwise  when  the  num- 
ber of  lines  through  the  coil  is  decreasing  and  contra- 
clockwise  when  increasing — this  to  a  person  looking  at 
the  coil  from  the  side  on  which  the  lines  enter  it. 

3.  The  amount  of  induced  E.  M.  F.  varies  directly  with 
the  time  rate  (i.  e. ,  the  rapidity)  of  change  of  the  num- 
ber of  lines  inclosed  by  the  coil. 

II.  Or,  the  laws  may  be  otherwise  stated  for  any 
straight  conductor  as,  for  instance,  any  short  length  of 
a  loop : 

1.  An  E.  M.  F.  is  induced  in  any  conductor  while  it  is 
cutting  across  lines  of  magnetic  force,  by  the  motion  of 
the  conductor  or  of  the  lines  or  of  both. 

2.  Hold  thumb,   forefinger  and  middle  finger  of  the 
right  hand,  each  at  right  angles  to  the  other  two.     If  the 


35.  Magnetic  Wind  Prom 
N.  to  S.  Pole. 


36.  The  Three  Positive  Directions  at 
Right  Angles. 


middle  finger  represents  the  conductor,  if 

the  forefinger  points  in  the  direction  of 

the  lines  of  (fore)  force,  and  if  the  thumb 

points  in  the  direction  the  conductor 

moves,  the  middle  finger  will  point  in 

the  direction  of  the  induced  E.  M.  F. 
3.  The  amount  of  E.  M.  F.  induced  varies 

directly  with  the  time  rate  (or  rapidity) 

with  which  the  number  of  lines  of  force 

is  cut. 
III.  An  alternating  current  is  usually 

generated  in  a  revolving  loop.    The  nega- 
tive part  can  be  rectified  in  the  outer 

circuit. 
1.  It  follows  from  either  set  of  the  above  laws  that  if  the  coil  in  fig.  37  revolves 

uniformly  as  the  brushes  point,  and  if  the  external  circuit  is  closed,  (1)  a  current 

will  be  generated  in  the  coil  due  to  the  induced  E. 
(2)  Its  direction,  during  the  entire  half  revolution  of 
which  the  coil's  position  is  shown  in  the  figure  mid- 
way, will  be  toward  the  brush  marked  -f ;  in  the 
next  half  revolution,  to  the  other  half.  (3)  The 
current  strengths  will  be  great- 
est at  both  vertical  positions, 
and  Oat  both  horizontals,  where 
their  direction  is  reversed. 

2.  The  current,  or  the  E.M.F., 
induced  during  little  more  than 
one  revolution,  is  expressed  by 


37.  Simple  A.  C.  Dynamo. 


38. 


the  curve  in  fig.  38.     That  part  of  the  curve  below  the  reference  line  represents 
the  negative  C  generated. 

3.  The  negative  C  may  be  rectified,  i.  e. ,  so  turned  as  to  go  to  line  as  a  positive 
C,  by  the  device  of  a  2-part  commutator  (fig.  39)  in  place  of  the  two  rings  of 

(42) 


THE   DYNAMO. 


43 


fig.  37.  The  two  parts  of  the  commutator  are  the  terminals  of  the  coil,  and 
so  disposed  that  each  brush  shall  pass  from  one  part  to  the  other  at  the  instant 
the  induced  current  changes  or  is  zero.  This  is  the  simplest  form  of  a  direct 
current,  self -exciting  dynamo,  such  as  the  fuse- 
firing  dynamo. 

4.  The  current  thus  sent  to  the  field  and  the 
external  circuit  consists  of  positive  pulsations  or 
waves,  shown  in  fig.  40. 

^^        — .  5.  In  order  to  render  the 

/    t    \  /    t  "\7*     positive  waves  less  abrupt, 
/     I     V     !     V        that  is,  to  make  the  dynamo 
"40^  current  more  nearly  like  a 

battery  current  represented 
by  the  broken  line  in  fig.  40,  it  is  only  necessary  to 
increase  the  number  of  armature  coils  and  of  com- 
mutator strips. 

6.  Principle  of  self-exciting  dynamos. — There  is 
usually  sufficient  magnetism  in  the  field  of  the 
soft-iron  field  magnet  core  to  give  rise  to  a  small 
current  in  the  armature  coil  when  revolved.  This  current  flowing,  wholly  or  in 
part,  through  the  winding  of  the  field  magnet,  increases  its  magnetism  and 
therefore  the  number  of  lines  of  force  in  the  field  between  the  poles.  The  cur- 
rent in  the  armature  coil  thereby  is  increased,  and  so  the  operation  continues 
intil  the  magnet  is  saturated  and  the  dynamo  gives  its  full  current. 

IV.  The  two  principal  armature  windings  are  the  ring  and  drum. 


39.  Simple  D.  C.  Dynamo. 


1.  Fig.  41  is  a  2-pole,  4-coil,  ring,  wind- 
ing around  core  of  annealed  soft  iron 
wires  or  washers.  Two  circuits  be- 
tween brushes.  Nearly  all  cores,  ring 
or  drum,  are  now  made  from  soft-iron 
sheet  in  washer  shape. 


42. 


Fig.  42  is  a  2-pole,  4-coil,  drum,  lap 
winding  over  annealed  soft-iron  wash- 
ers starting  from  1.  Coil  a  b  is  firsl 
wound,  then  c  d,  e  f,  g  h  in  order. 
Back  pitch,  -f  3;  front  pitch,  — 2. 


43. 


Fig.  43  is  a  2-pole,  8-coil,  ring  wind- 
ing. Arrows  show  direction  of  cur- 
rents. 


44. 


Fig.  44  is  a  2-pole,  8-coil,  lap,  drum 
winding.  Back  pitch,  -f-  7 ;  front  pitch, 
—  5. 


44 


HANDBOOK    FOR   ELECTRICIANS. 


Fig.  45  is  a  4-pole,  20-coil,  ring,  four 
windings  through  armature,  making 
its  resistance  between  poles  =  -fa  of 
that  of  the  single  winding.  By  con- 
necting each  bar  of  the  commutator 
with  the  one  opposite,  two  brushes 
90°  apart  will  be  sufficient. 


Fig.  46  is  a  4-pole,  17-coil,  wave,  drn  m 
winding.  Back  pitch,  9 ;  front  pitch.  9. 
Two  circuits  between  brushes.  Short 
lines  having  arrowheads  represent 
wires  along  the  length  of  the  cylinder ; 
outside  wires  are  back  connections, 
inside  wires,  front  connections. 


2.  An  armature  winding  is  more  readily  followed  by  considering  the  wires, 
bars  and  poles  rolled  out  upon  a  plane  surface  as  in  fig.  47,  for  the  armature 
shown  in  fig.  48.  Or,  upon  paper,  draw  rectangles  to  represent  all  poles,  in  a 
parallel  row  show  all  of  the  bars,  and  then  draw  single  lines  from  the  bars  to 
represent  the  coils  as  they  are  found  on  the  cylinder  in  one  position. 


48.  Drum  Wave  Windlng-4-Pole. 


47.  Drum  Wave  Rolled  Out. 


3.  The  features  of  recent  slow  speed  armatures  are — 

(a)  The  core  is  composed  of  japanned  washer- 
shaped  discs  stamped  out  of  sheet  iron  and  solidly 
assembled  on  a  spider  (fig.  52).  Air  ventilating 
ducts  run  radially  and  longitudinally  through  the 
core,  and  deep  slots  in  which  the  coils  are  to  be  laid 
run  longitudinally  along  the  cylinder  surface. 

(6)  The  copper  coils  (figs.  51  and  53)  are  forged  or 
formed  on  a  collapsible  block,  then  covered  with  tough 
and  moisture-proof  insulation  and  laid  in  lap  form 
(fig.  50),  or  in  wave  form  (fig.  52)  in  the  slots  between 
the  teeth  of  the  cylinder  core  where  they  are  so  firmly 
wedged  by  fiber  and  bound  by  band  wires  that  no  part 
can  vibrate. 

(c)  Opposite  active  parts  of  the  same  coil  occupy  as 
nearly  as  possible  corresponding  positions  (figs.  50  and 
52)  under  the  poles.  Ends  of  coils  are  mechanically 
fastened  and  soldered  to  their  proper  bars  so  that  open 
circuit  may  not  occur.  Back  and  front  wires  are 
equal.  The  air  space  is  everywhere  the  same  and  the 
pull  of  all  field  magnets,  alike.  This  method  of  wiring 
requires  a  minimum  of  length  and  allows  any  injured 
51.  One  Lap  Coil.  Coil  to  be  easily  replaced. 


49.  W=e  M.  P.  Generator  Armature,  with  Winding  Unfinished. 


50.  Q.   E.  Core.    Lap  Winding  Begun. 


THE    DYNAMO.  45 

(d)  The  bars  of  the  commutator  (fig.  54),  of  H.  D.  copper  insulated  by  amber- 
colored  mica,  are  sufficient  in  number  to  keep  the  P.  D.  between  any  two  adjacent, 
below  10  volts. 

(e)  The  bearings  (fig.  55)  are  self -aligning,  also  self-oiling  by  means  of  revolv- 
ing rings  on  the  shaft. 


Out-er  mica  cones>. 


Inner-  mica  cone 


,-__/ 


-mica  collar-   under-  seamen' 
Cap 


-Snell 


54.  General  Electric  Commutator. 


V.  Field  windings. — There  are  five  methods  of  exciting  the  magnet  which 
in  turn  render  magnetic  the  space  or  field  in  which  the  armature  coils  revolve : 
Permanent  Magnets  (fig.  60),  Separately  Excited  (fig.  56),  Series  (fig.  57),  Shunt 
(fig.  58),  and  Compound  Winding  (fig.  59). 


56. 


57. 


58. 


46 


HANDBOOK    FOR    ELECTRICIANS. 


The  series  winding  is  regulated  by  varying  the  resistance  of  a  coil  in  shunt 
to  it.  The  shunt  winding  is  regulated  by  varying  the  resistance  of  a  coil  in 
series  with  it.  The  compound  winding  uses  both  methods  of  regulation. 

(B)    SPECIAL    SERVICE    GENERATORS. 

I.  The  telephone  call  box  dynamo  (fig.  60)  has 
three  permanent  magnets  M  to  create  its  field. 
The  single  Siemens  armature  coil  C,  of  fine  wire, 
has  one  end  fastened  to  the  soft-iron  core  at  a  and 
the  other  end  to  the  insulated  pin  c.  The  alter- 
nating current  generated  passes  out  through  c  to 
a  spring  in  contact  with  it  and  returns  through 
frame  and  bearing  to  a. 


II.  United  States  fuse-firing  dynamo  (fig.  61) 
is  series  wound,  self-exciting.  The  Siemens 
armature  coil  is  revolved  eight  times  by  means 
of  its  pinion  gearing  into  the  ratchet  bar  R  when 
pushed  down.  At  the  end  of  the  stroke  the  bar 
strikes  and  opens  the  short-circuiting  key  P  and 
allows  the  full  current  to  rush  into  the  external 
circuit.  No.  3  (16  by  8  by  5  inches)  weighing 
18  pounds,  has  0.05-inch  wire  in  magnet  (If  ohms), 
and  0.032-inch  wire  in  armature  (0.9  ohms), 
develops  15  volts  and  will  fire  eight  fuses  in 
series. 

(7=15-4-  (2.7 


i-n  ^ 


fti^- 

_  &          ^(Sj 

JWw.^ 

*  — 

EEE=Frf 

^ 

• 

8                         *!.''         f 

-Yiv 

Q..J 

61.  Dynamo  for  Firing  Fuses.  Second  View  of  Circuits. 

Ill — GENERAL  ELECTRIC  DIRECT-COUPLED  GENERATING  SETS. 

1 .  Foundations — Installing.  — The  generating  set  (fig.  62)  should  be  provided  with 
a  foundation  of  ample  proportions  and  mass  to  absorb  the  vibrations  produced 
by  the  reciprocating  parts  of  the  engine.  When  placed  upon  a  good  foundation, 
the  set  will  give  the  best  results,  require  the  least  amount  of  attention,  the  bear- 
ings will  run  perfectly  cool  with  a  small  amount  of  oil,  and,  in  general,  operating 
expenses  will  be  reduced  to  a  minimum. 


OF  THE 

UNIVERSITY 

OF 


63.  Governor. 


THE   DYNAMO. 


47 


The  engines  should  run  without  perceptible  vibration  or  noise  if  properly 
installed  and  given  a  reasonable  amount  of  attention.  When  a  generating  set 
is  installed,  in  a  building  for  isolated  light  or  power,  care  should  be  taken  to 
avoid  haying  the  engine  foundation  connected  in  any  way  to  the  foundation 
of  the  building  or  its  adjacent  walls.  Pipes  leading  to  the  engine  should  also 
be  as  free  as  possible  from  connection  to  walls.  A  wooden  base  frame  is  some- 
times found  desirable  under  the  generating  set  when  installed  in  a  building,  as 
it  will,  to  a  large  extent,  prevent  the  transmission  of  noise  and  vibration. 

2.  .Steam  pipes,  pressure  and  speed. — Sharp  bends  in  the  steam  and  exhaust 
pipes  should  be  avoided  as  much  as  possible,  and  the  steam  pipe  should  be 
covered  with  good  nonconducting  material.  A  drain  pipe  with  valve  should 
be  provided  just  above  the  throttle  valve  in  order  to  drain  the  pipe  line  of  con- 
densed water.  A  separator  should  be  installed  on  the  steam  pipe  close  to  the 
engine,  to  protect  it  from  water  that  is  occasionally  carried  over  with  the 
steam.  Often  considerable  trouble  is  experienced  with  foaming  boilers,  and 


62.    M.  P.  6-20-305-125.    Form  of  G.  E.  Generating  Set,  with  Single 
1 1  by  8  inch  Cylinder. 

accidents  are  liable  to  happen  if  no  separator  is  used.  When  the  engines  are  fun 
noncondensing,  a  drain  pipe  £  inch  to  f  inch  in  diameter,  depending  upon  the 
size  of  the  engine,  should  be  placed  at  the  lowest  point  of  the  exhaust  pipe. 

3.  The  engine. — (a)  The  engine  and  generator  are  tested  for  several  hours 
with  the  full  rated  output  of  the  generator,  and  the  engine  is  regulated  to  the 
proper  speed,  which  is  stamped  on  the  name-plate.  The  valves  of  single  engines 
are  set  to  operate  economically  at  a  steam  pressure  of  80  pounds,  and  the  ratings 
of  single  engines  are  based  on  80  pounds  steam  pressure,  noncondensing.  Ver- 
tical tandem  compound  engines  (fig.  73)  are  adjusted  to  operate  at  125  pounds 
steam  pressure,  condensing,  or  140  pounds  noncondensing,  and  the  sets  are  rated 
on  this  basis.  Both  single  and  compound  engines  give  the  best  results  when 
operated  at  their  rated  pressures,  and  if  an  engine  is  desired  to  run  at  a  steam 
pressure  lower  than  standard,  it  may  be  necessary  to  adjust  the  governor  (fig.  63) 
by  tightening  the  spring  until  the  rated  speed  is  obtained.  Single  engines  may 
be  run  on  a  steam  pressure  up  to  100  pounds  without  difficulty,  but  for  higher 
pressures  use  reducing  valves. 


48  HANDBOOK    FOR   ELECTRICIANS. 

(&)  If  the  speed  of  the  engine  is  unsteady,  the  cause  is  probably  sticking  of 
the  valve  or  parts  of  the  governor,  or  loose  connections  in  the  valve  motion. 
The  governor  should  be  taken  apart,  bearings  thoroughly  cleaned,  and  the  lubri- 
cant removed.  Only  the  best  quality  of  thin  grease — mixed  with  cylinder  oil  if 
desired— should  be  used  in  the  governor. 


64.  Piston  Rod  and  Crosshead. 


65.  Governor  Connecting  Rod. 


66.  Piston  Valve— 20  KW.  and  Over. 


67.  Piston  Valve— Below  20  KW. 

(c)  The  governor  (fig.  63)  has  few  moving  parts  and  minimum  friction.  As 
the  load  is  decreased,  the  fly  weight,  by  increased  centrifugal  force,  is  moved 
out  and  the  eccentric  pin  (seen  near  the  center  hole  of  the  fly  wheel)  is  moved 
toward  the  center  of  the  shaft.  This  reduces  the  throw  of  the  valve,  changes 
the  steam  admission  and  compression  to  suit  the  load,  and  preserves  the  engine 
speed  within  small  limits. 

The  governor  can  change  the  cut-off  from  £  to  0,  and  the  speed  can  be  changed 
within  certain  limits  by  tightening  or  loosening  the  spring.  It  will  not  allow, 
with  80  pounds  steam,  a  variation  exceeding  2£  per  cent  in  the  number  of  its 
revolutions  for  a  change  from  full  load  to  one-fifth  of  the  same ;  nor  exceeding 
3^  per  cent  for  a  change  from  80  to  100  pounds  pressure ;  nor  exceeding  5  per 
cent  for  both  changes. 


THE   DYNAMO. 


49 


((7)  The  relief  valves  for  taking  care  of  the  water  that  enters  the  cylinder 
should  be  adjusted  for  the  working  pressure  at  the  engine,  and  should  open  freely 
at  a  pressure  5  pounds  greater. 

(e)  If  any  valves  leak,  they  should  be  taken  out  and  cleaned,  and  the  seats 
reground.  "  The  leak  should  not  be  stopped  by  increasing  the  pressure  on  the 
valves. 

(/)  The  engine  will  run  without  noise,  vibration  or  heating  in  any  of  its  parts 
when  given  proper  care  and  attention.  All  working  surfaces  are  liberally  pro- 
portioned, and  wear  is  very  slight,  but  as  soon  as  any  loss  motion  appears,  it 
should  be  immediately  taken  up  by  the  adjustment  provided  for  that  purpose. 
Use  only  Garlock  equare  or  other  first-class  packing,  and  the  best  quality  of 
cvlinder  oil. 


h 


68.  Counter=C!ockwise  Rotation.  69.  Engine  Side. 

4.  The  generator — (a)  To  place  the  spools. — Observer  is  supposed  to  be  inside 
of  frame  and  looking  at  faces  of  two  lower  pole  pieces.  Large  arrow  indicates 
direction  of  rotation  of  lower  half  of  armature.  Small  arrows  correspond  to 
arrows  on  spool  flanges,  the  spools  being  so  placed  that  the  arrows  point  in  oppo- 
site directions  on  each  succeeding  spool.  Arrows  on  bearings  must  point  in 
direction  of  rotation. 

(6)  To  adjust  the  compounding. — Every  compound  generator  is  provided 
with  a  shunt  consisting  of  strips  of  German  silver  with  suitable  terminals 
attached,  which  should  be  connected  to  the  series  field  terminals  on  the  right- 
hand  side  facing  the  commutator  (fig.  68).  Any  degree  of  compounding  up  to 


70.  Freeing  the  Pigtail  from  the  Brush  Holder. 


1714 — t 


50 


HANDBOOK   FOR   ELECTRICIANS. 


10  per  cent  may  be  obtained  by  changing  the  length  of  this  shunt.  The  arma- 
ture and  field  coils  are,  during  winding,  subjected  to  an  insulation  test  with  a 
voltage  many  times  higher  than  the  normal  and  their  resistance  is  watched  to 
locate  short  or  open  circuits. 

(c)  To  set  the  brushes,  place  the  brush  holder  on  the  studs  so  that  the  boxes 
A  (see  fig.  70)  which  hold  the  brushes,  shall  be  about  •£  inch  from  the  surface 
of  the  commutator,  and  clamp  them  firmly  in  this  position.  From  time  to 
time  the  brush  holder  should  be  turned  slightly  on  the  studs  to  compensate  for 
the  wear  of  the  commutator. 

Place  the  brushes  in  the  holders,  as  shown  in  fig.  71,  and  screw  down  the 
pressure  spring  B  by  turning  the  nut  C,  so  as  to  give  about  l£  pounds  pressure 
for  1^-inch  brushes  and  £  pound  for  f-inch  brushes.  Nothing  is  gained  by 
increasing  the  pressure  per  square  inch  on  a  carbon  brush  above  2  pounds,  as 
the  resistance  per  square  inch  beyond  this  point  is  practically  not  reduced, 
whereas,  the  friction  is  increased  in  direct  proportion  to  the  pressure. 

Fit  the  carbon  brushes  carefully  to  the  commutator  by  passing  beneath  them 
No.  0  sandpaper,  the  rough  side  against  the  brush  and  the  smooth  side  held 
down  closely  against  the  surface  of  the  commutator.  Move  the  sandpaper  in 
the  direction  of  rotation  of  the  armature,  and  on  drawing  it  back  for  the  next 


71.  Correct  Position  of  Brushes  in  Brush  Holder. 

cut,  raise  the  brush  so  as  to  free  it  from  the  sandpaper,  then  lower  the  brush 
and  repeat  the  operation  until  a  perfect  fit  is  obtained.  If  the  brush  requires 
considerable  sandpapering,  No.  2  sandpaper  may  be  used  at  first,  but  the  final 
fitting  must  be  done  with  No.  0.  If  an  attempt  be  made  to  fit  the  brushes 
without  raising  them  when  drawing  the  sandpaper  back,  it  will  in  every  case 
fail  to  give  satisfactory  results.  When  thick  brushes  are  used — say  f-inch — in 
addition  to  following  the  above  instructions,  the  machine  should  be  run  as  long 
as  convenient  without  load  in  order  to  improve  their  surface.  As  soon  as  the 
brushes  of  a  set  appear  to  make  a  good  fit  one  of  them  should  be  removed  from 
the  brush  holders  in  the  following  manner,  to  determine  if  they  are  worn  to  a 
surface : 

Unscrew  the  stud  D,  thereby  freeing  the  end  of  the  pigtail  E,  and  push  the 
spring  B  forward  so  that  there  will  be  plenty  of  room  to  draw  the  tip  E  on  the 
end  of  the  pigtail  through  the  slot  F  (see  fig.  70).  Then  draw  the  pigtail 
through  the  slot  F,  bend  it  forward  and  turn  the  spring  B  to  one  side  as  shown 
in  fig.  72.  The  brush  may  then  be  withdrawn  from  the  box.  In  replacing  the 
brush  these  directions  should  be  followed  in  reverse  order. 

Care  should  be  taken  not  to  disturb  the  nut  C  after  it  has  once  been  set,  as  it 
is  not  necessary  to  alter  the  pressure  of  the  spring  B  in  removing  or  replacing  a 
brush.  By  this  means  a  practically  constant  pressure  may  be  kept  on  the  brush. 

(d)  To  adjust  the  brush  yoke. — The  design  of  these  machines  is  such  that  no 
movement  of  the  brushes  is  necessary  when  load  is  thrown  off  or  on.     The 
brushes  should  be  set  at  no  load,  so  that  the  reference  mark  on  the  pedestal  is 
in  line  with  the  reference  mark  on  the  brush-holder  yoke.     With  the  brushes  in 
this  position  generators  will  compound  according  to  the  name-plate  stamping. 

(e)  To  take  care  of  commutator. — The  commutator,  brushes  and  brush  holders 
should  at  all  times  be  kept  perfectly  clean  and  free  from  carbon  or  other 


73.  Small  Direct=Coupled  M.  P.  6=25=450,  with  Vertical  Tandem 

Compound  Engine.  50 


THE   DYNAMO. 


51 


dust.  Wipe  the  commutator  from  time  to  time  with  a  piece  of  canvas,  lightly 
coated  with  vaseline.  If  vaseline  is  not  at  hand,  use  oil,  but  lubricant  of  any 
kind  should  be  applied  very  sparingly. 

If  a  commutator  when  set  up  begins  to  give  trouble  by  roughness  with 
attendant  sparking  and  excessive  heating,  it  is  necessary  to  immediately  take 
measures  to  smooth  the  surface.  Any  delay  will  aggravate  the  trouble  and 
eventually  cause  high  temperatures,  throwing  of  solder  and  possibly  displace- 
ment of  the  segments.  No.  0  sandpaper  fitted  to  a  segment  of  wood  with  a 
radius  equal  to  that  of  the  commutator,  if  applied  in  time  to  the  surface  when 
running  at  full  speed  (and  if  possible,  with  brushes  raised),  and  kept  moving 
laterally  back  and  forth  on  the  commutator,  will  usually  remedy  the  fault.  If 
this  does  not  suffice,  it  will  then  be  necessary  to  tighten  up  the  segments  and 
turn  them  off  true.  A  machine  tool  will  not  leave  the  surface  smooth  enough 
to  give  perfectly  satisfactory  results.  It  is  always  necessary  before  putting  on 
the  load  after  the  commutator  has  been  turned,  to  carefully  smooth  the  surface 
with  the  finest  sandpaper,  thus  removing  all  traces  of  the  tool  point. 


72.  The  Brush  Ready  for  Removal. 

5.  Starting  and  running  the  set. — (a)  Before  starting,  see  that  all  screws  and 
nuts  are  tight,  that  the  oil  cups  are  filled  with  oil  free  from  dirt  and  grit, 
and  that  all  working  parts  are  well  oiled.  The  feed  should  then  be  adjusted  to 
give  the  required  amount  of  oil  to  each  bearing.  The  waste  oil  collects  in  the 
base  and  may  be  used  again  after  running  through  a  filter  with  some  new  oil 
added,  but  no  advantage  results  from  using  too  much  oil.  Turn  the  armature 
by  hand  to  see  that  it  is  free  and  does  not  rub  or  bind  at  any  point.  The  drain 
valves  on  the  cylinder  should  all  be  opened  to  allow  the  condensed  water  to 
escape.  Turn  the  steam  on  slowly  at  first,  allowing  the  cylinder  to  get  well 
warmed  up  and  giving  the  condensed  water  a  chance  to  get  out  before  turning 
on  full  steam  pressure.  The  piston  valve  will  heat  up  as  soon  as  the  steam 
enters,  but  the  cylinder  requires  some  time  before  it  expands  sufficiently  to 
allow  the  valve  to  move  freely.  When  the  engine  has  started,  see  that  the  oil 
rings  in  the  bearings  are  in  motion. 

(b)  As  soon  as  the  machine  is  set  running  see  that  it  excites  itself  to  full  volt- 
age.    If  it  does  not,  trace  out  the  field  connections  smd  test  the  polarity. 

When  the  machine  is  to  run  in  parallel  with  others  and  its  polarity  is  wrong, 
raise  the  brushes  and  excite  the  fields  by  closing  the  main  switch  from  the 
bus  bars. 

(c)  A  continuous  run  of  four  hours  on  full  load  should  not  raise  the  tempera- 
ture of  an  armature  or  field  coil  60°  F.,  or  of  the  commutator  72°  F.,  above  the 
air  as  determined  by  placing  the  bulb  of  a  thermometer  surrounded  by  waste 
upon  it  after  the  machine  is  stopped.     Directly  following  the  above,  the  machine 
will  sustain  a  heat  run  continuously  of  two  hours  on  33  per  cent  above  its  full 
rated  load  without  injury  to  the  engine  or  dynamo.     After  this  run  which 
should  only  be  done  by  an  experienced  person,  it  is  a  good  time  to  make  the 
insulation  tests  and  to  look  for  mechanical  defects. 

(d)  To  remove  the  armature,  unbolt  and  lift  off  the  upper  field  half,  take  off 
the  brush  holders,  brush  yoke,  pulley  and  bearing  caps,  and  put  a  sling  on  the 
armature. 


52  HANDBOOK   FOR   ELECTRICIANS. 

(C)  DISEASES  OF  DYNAMOS. 

The  DISEASES  are  stated  in  small  capitals,  their  causes  in  italics ;  the  remedy 
follows  the  cause  when  it  is  not  evident  and  not  structural.  Dr.  F.  B.  Crocker 
gives  the  following  systematic  statement : 

I. — SPARKING  AT  THE  COMMUTATOR  is  caused  by: 

1.  Armature  carrying  too  much  current. — Due  to  overload,  loose  connections, 
reversed  polarity,  excessive  voltage  of  current,  short  circuit  or  grounds  in 
dynamo  or  external  circuit. 

2.  Brushes  not  at  the  neutral  points. — Shift  the  rocker  to  a  point  midway  of 
those  which  give  sparking. 

3.  Commutator  rough. — Apply  No.   0  sandpaper  (not  emery)  laid  inside  a 
wooden  form  to  fit  the  commutator,  and  before  replacing  brushes  take  care  to 
remove  all  traces  of  sand  or  copper  dust. 

4.  Commutator  very  rough  or  eccentric  or  having  aflat  bar.  —  Turn  the  commu- 
tator down,  revolving  slowly  in  its  place  without  play,  by  means  of  a  sharp- 
pointed  tool,  and  finish  in  turn  with  a  smooth  flat  file  and  emery ;  preferably  put 
armature  in  a  lathe.     A  flat  is  often  caused  by  an  open  coil. 

5.  A  high  bar.  —  Tap  it  down  and  tighten  up  the  clamping  ring,  or,  if  it  can 
not  be  done,  file  the  bar  down. 

6.  Brushes  making  bad  contact. — Due  to  roughened  or  burned  ends,  improper 
bedding,  to  oil,  carbon,  dust,  or  to  insufficient  pressure. 

7.  A  short  or  broken  circuit  in  armature  or  field;  a  reversed  coil. 

8.  A  ground  in  the  armature. — Locate  and  replace  the  coil. 

9.  A  weak  field  or  excessive  shunt  field  resistance. 

10.  Unequal  poles  due  to  armature  reaction  being  relatively  too  great. 

11.  Too  high  brush  resistance,  as  with  certain  carbons.    * 

12.  Vibration,  from  unbalanced  armature  or  pulley  or  faulty  belt. 

13.  Chatter  of  carbon  brushes. — Clean  commutator  and  apply  vaseline  or  oil. 

14.  Surging  current,  from  uncertain  engine  governor  action. 

15.  Break  in  armature,  only  while  running  due  to  centrifugal  force. 

II. — HEATING  OF  COMMUTATOR  AND  BRUSHES  is  caused  by: 

1.  Heat  from  adjoining  bearing  or  from  armature. 

2.  Sparking. 

3.  Black  carbon  film  from  the  brushes,  which  offers  resistance. 

4.  Bad  connections  in  brush  holder. 

5.  Arcing  between  bars  or  other  parts  of  the  commutator. 

6.  Heating  of  carbon  brushes  from  current. — Coat  the  carbons  with  copper 
deposit. 

III.— HEATING  OF  ARMATURE  OR  FIELD  MAGNET  is  caused  by: 

1.  Excessive  current. — Same  as  cause  1  of  sparking. 

2.  Coils  short-circuited  permanently,  or  due  to  contact  in  armature  only  while 
running. 

3.  Moisture. — Showing  vapor  driven  off  after  a  short  run.     Bake  in  an  oven  or 
send  full  current  until  vapor  ceases. 

4.  Foucault  currents  in  iron  core  or  Eddy  currents  in  the  coils,  structural. 

5.  Reversed  coils. — Send  a  current  through  armature  or  field  and  note  the 
deflections  of  a  compass  needle  all  the  way  around. 

6.  Heat  from  adjacent  parts. 

IV. — HEATING  OF  BEARINGS  is  caused  by: 

1.  Lack  of  good  mineral  oil. 

2.  Grit  or  dirt. 

3.  Shaft  bearing  rough  or  cut. 

4.  Bearings  too  tight. 

5.  Shaft  sprung,  so  that  it  turns  harder  at  one  point  of  a  revolution. 

6.  Bearings  out  of  line  or  proportion. 

7.  Side  thrust  of  shaft  against  bearings. 

8.  Too  tight  belt. 

9.  Armature  closer  to  one  pole  than  to  another. 

10.  Heat  from  adjacent  part. 

V. — ABNORMAL  NOISE  is  caused  by: 

1.  Armature  or  pulley  out  of  balance.     Bad  foundations. 

2.  Armature  striking  a  pole  piece;  rebabbitting,  new  liners,  or  reducing  the 
projecting  part. 


THE   DYNAMO.  53 

3.  Side  thrust  of  shaft  due  to  bad  alignment. 

4.  Rattling  of  loose  screws  or  other  parts. 

5.  Humming  or  squeaking  of  brushes.— Lift  one  of  a  set  off  at  a  time  and, 
when  found,  apply  a  drop  or  two  of  oil. 

6.  flapping  or  slipping  of  belt,  or  striking  of  a  belt  joint  on  the  pulleys. — 
Tighten  or  loosen  the  belt ;  never  apply  resin. 

7.  Humming  of  armature  teeth  passing  the  edge  of  pole  pieces. 

8.  Straining  of  coupling  in  direct  connected  sets.     Reline  and  readjust. 

VI. — SPEED  TOO  Low  is  caused  by: 

1.  Overload. 

2.  Short  circuit  in  armature. 

3.  Armature  striking  pole  pieces. 

4.  Shaft  not  free  to  revolve. 

5.  Engine  too  slow  or  slipping  belts. 

VII.— FAILURE  TO  GENERATE  is  caused  by: 

1.  Residual  magnetism  too  weak,  due  to  (a)  vibration,  (b)  proximity  of  another 
dynamo,  (c)  earth's  magnetism,   (d)  accidental  reversed  current  through  field 
coils,  but  not  sufficient  to  reverse  the  magnetism.     Send  a  current  from  a  few  cells 
through  the  field  coils  in  the  proper  direction. 

2.  Reversed  connections,  or  direction  of  rotation. 

3.  Short  circuit  to  a  shunt  dynamo. 

4.  Field  coils  opposed.     A  compass  needle  will  show. 

5.  Open  circuit  in  dynamo,  at  a  brush  contact,  switch  or  fuse,  or  in  the  exter- 
nal circuit  to  a  series  machine. 

6.  Brushes  not  in  proper  position. 

VIII.  — VARIATION  OF  VOLTAGE  is  caused  by : 

1.  Irregular  speed. 

2.  Lap  or  other  bad  belt  joints. 

3.  Short  or  open  circuits  in  armature  or  field. 

4.  Incorrect  connections. 

5.  Engine  governor  out  of  order. 

(D)  THE  CARE  AND  MANAGEMENT  OF  D.  C.  DYNAMOS. 

It  is  assumed  that  the  machinery  is  properly  constructed  and  installed.  The 
engineer  on  taking  charge  and  subsequently  at  intervals  makes  an — 

1.  Inspection  and  adjustment. — Every  part  of  an  electric  plant  is  kept  scrupu- 
lously clean  if  well  managed. 

The  caps  of  bearings  are  taken  off ;  all  dirt,  grit  and  old  oil  are  removed ;  oil 
passages  are  cleared ;  the  journals  are  examined ;  the  caps  are  screwed  back  with- 
out binding ;  the  boxes  are  filled  with  the  best  mineral  oil. 

The  armature,  rotated  by  hand,  is  examined  for  injured  insulation,  a  bulge, 
loose  coil  or  binding  wire,  contact  with  pole  piece,  unequal  distance  between 
armature  and  pole  pieces  due  to  wear  or  bent  axle,  contact  between  lug,  tendency 
to  stop  in  the  same  place. 

A  good  commutator  is  cylindrical,  smooth,  and  clean,  and  has  a  dark-brown 
polished  appearance.  A  high  bar  must  be  filed  down.  For  a  low  bar  or  flat, 
the  whole  commutator  must  be  turned  down.  A  rough  surface  from  excessive 
sparking  can  be  smoothed  by  fine  sandpaper  (not  emery)  laid  inside  a  wooden 
form  cut  out  to  fit  the  cylinder  which,  after  the  brushes  are  raised,  is  given  a 
slow  speed ;  before  letting  down  the  brushes,  make  sure  that  no  metal  dust  or 
filings  lie  in  the  insulation  between  the  bars.  If  the  commutator  has  worn 
eccentric  or  in  ruts,  it  must  be  turned  down  by  a  tool  on  a  sliding  rest  fastened 
to  the  bed. 

The  brushes,  copper  or  carbon,  with  ends  alike  beveled  and  evenly  bedded  on 
the  commutator,  should  set  with  tips  exactly  180  degrees  apart  in  2-pole  machines, 
90  degrees  in  4-pole,  etc. ,  in  perfect  alignment  and  at  equal  lengths  from  each 
rocker  arm  along  which  the  brushes  are,  as  a  rule,  unevenly  spaced  so  that  the 
wear  on  the  whole  commutator  will  be  as  nearly  uniform  as  possible.  In  the 
absence  of  setting  marks,  adjust  the  tips  of  one  set  of  brushes  carefully  to  the 
edge  of  a  bar  and  count  the  bars  for  the  exact  position  of  the  other  set. 

The  brush  springs  are  next  adjusted  to  a  uniform,  light,  yet  reliable,  contact 
sufficient  to  take  the  full  current  without  sparking.  Too  great  pressure  will 
soon  wear  and  heat  the  commutator  and  cause  sparking ;  too  light  pressure  will 


54 


HANDBOOK   FOR   ELECTRICIANS. 


cause  vibration,  sparking  and  heating.  Pressure  of  carbons  seldom  exceed  1 
pound  per  square  inch  of  contact  surface  and  is  usually  less ;  of  copper  brushes, 
is  much  less. 

See  that  the  rocker  can  with  steady  force  be  moved  over  its  range,  can  be  locked 
in  any  position,  and  that  no  side  play  of  it  disturbs  the  bedding  of  the  brushes. 

Oil,  water,  grit  or  dust  on  any  conductor  insulation  or  part  of  the  machine, 
a  wrong  or  a  bad  connection,  an  unsoldered  joint,  a  loose  nut  or  bolt,  or  a  tin 
oil  can,  tool,  or  loose  iron  near  the  machine  will  be  quickly  detected  by  a  capable 
engineer  and  removed. 

Dynamos  usually  run  counter  clockwise  to  a  person  at  the  commutator  end. 
To  reverse  the  rotation,  shift  the  positive  brush  with  its  connections  to  the  posi- 
tion of  the  negative,  likewise  shifted.  To  reverse  the  current,  exchange  the 
leads  or  reverse  the  polarity. 

A  belt  should  be  heavy,  single,  or  link,  ^-inch  narrower  than  pulley,  without 
lace  or  lap,  and  just  tight  enough  to  prevent  slipping.  The  pull  is  always  on 
the  lower  run.  It  remains  on  the  pulleys  in  intervals  between  daily  runs  of  the 
dynamo  slid  back  6  inches. 

Nand.8  are  labeled  or  marked  by  the  engineer  on  magnets;  -J-  and  — ,  on 
terminals;  "on "and  "off,"  on  rheostats;  initial  letters  of  connections,  on  volt- 
meter switch  points ;  currents  on  feeders,  etc. ,  for  his  aid  in  case  of  trouble. 

The  inspection  extends  also  to  a  run  of  the  plant. 

STARTING. 

2.  See  that  all  parts,  screws,  and  nuts  are  tight;  turn  the  armature  by  hand 
to  see  that  it  is  free  and  does  not  rub  or  bind;  put  on  the  belt,  tightening 
gradually  after  starting.  Note  that  the  main  switch  to  line  is  open  for  shunt 
or  compound  machines  and  closed  for  a  series ;  that  the  field  rheostat  is  open 
and  the  V.  switch  is  turned  to  dynamo  -+-  and  — ;  fill  oil  reservoirs  and  start 
lubricators  if  sight  feed;  start  the  machine  very  slowly,  noting  that  the  oil 
rings  turn  and  belt  runs  smoothly ;  bring  it  gradually  to  full  speed ;  drop  the 
brushes  down  if  not  there  permanently ;  close  field  rheostat  and  cut  put  resist- 
ance for  a  gradual  rise  of  potential,  as  shown  by  the  voltmeter  or  pilot  lamp, 
to  the  proper  limit ;  stand  ready  to  stop  if  anything  goes  wrong ;  shift  the  brushes 
at  the  first  sign  of  sparking. 

To  light  lamps  raise  the  dynamo  to  its  voltage  and  close  in  order  and  deliber- 
ately the  overload,  main,  and  feeder  switches,  watching  the  ammeters  whose 
deflections  should  be  anticipated.  Of  the  feeders,  close  smaller  first,  if  there  is 
a  choice,  to  increase  the  load  as  steadily  as  possible. 

Before  closing  a  feeder  on  a  storage  battery,  find  the  battery's  voltage  and 
make  sure  that  the  voltage  of  the  dynamo  is  5  to  10  volts  greater,  while  at  the 
same  time  the  lamps  are  kept  at  their  normal  voltage  by  the  heavy  current 
regulator. 

A  new  or  a  repaired  machine  is  first  run  empty,  or  on  light  load  several  hours 
with  slack  belt  and  plenty  of  oil. 

If  two  compound  machines  are  in  parallel  (fig.  75),  start  and  close  one  on  the 
main  circuit  as  above ;  bring  the  other  to  normal  speed ;  close  its  field  rheostat 


Stuitch  or  Rheostat 


to  excite  its  shunt  field ;  next  close  equalizing  switch  and  regulate  with  shunt 
field  rheostat  to  the  potential  of  the  first  machine;  then  close  main  switch. 
Ammeters  will  show  if  either  is  doing  its  share  of  the  work.  To  stop,  reverse 
the  above  steps. 


THE   DYNAMO.  55 

RUNNING. 

3.  A  dynamo  properly  started  and  subsequently  watched  requires  little  care. 
Any  trouble  should  be  detected  at  its  beginning  and  corrected,  if  possible, 

without  stopping.  Sparking  is  the  worst  trouble.  Allow  no  unusual  or 
unnecessary  noise  to  continue,  nor  change  of  voltage  or  speed,  nor  abnormal 
heating  of  bearings,  field  coil,  armature  or  commutator.  The  heating  of  any 
part  which  the  hand  can  bear  indefinitely  without  discomfort  is  safe.  The 
limit  in  modern  dynamos  and  motors  is  80°  F.  of  any  part  above  the  room ;  if 
greater  than  this,  something  is  wrong. 

Feel  the  air  near  the  armature  revolving.  The  commutator  should  not  be 
more  than  10  degrees  warmer  than  the  armature. 

Overloading  is  the  cause  of  most  troubles. 

Handle  a  conductor  with  a  stick  or  insulated  tool.  Use  one  hand  only  around 
a  dynamo.  Wear  rubber  gloves  and  shoes  for  500  volts  or  more. 

Stop  the  dynamo  if  violent  armature  sparking  can  not  be  suppressed  or  smok- 
ing appears. 

In  good  dynamos  the  "lead'?  is  small  and  the  rocker  has  a  wide  range  with- 
out sparking.  Its  proper  position  is  midway  of  the  two  points  which  shows  the 
first  sparking  or  at  that  point  which  gives  the  highest  voltage.  Leave  the 
rocker  always  clamped. 

The  lead  of  dynamo  brushes  advances  slightly  with  rotation  as  the  load 
increases. 

One  of  two  or  more  brushes  in  a  set  may  be  removed  and  cleaned  while  run- 
ning. If  carbon  brushes  "chatter,"  clean  the  commutator. 

The  oil  on  a  new  or  repaired  dynamo  is  drawn  off  after  each  run  for  three  or 
four  days  to  get  rid  of  the  grit.  Afterwards  draw  off  and  add  a  little  fresh  oil 
every  three  or  four  weeks. 

In  case  of  a  hot  box,  do  not  shut  down  unless  the  following  alternatives  have 
failed :  Slacken  the  belt,  loosen  the  cap,  put  more  oil  on,  lubricate  with  vase- 
line or  cylinder  oil.  If  the  heating  is  reduced,  polish  the  shaft  with  crocus 
cloth  and  scrape  the  boxes  after  shutting  down.  But  if  the  heating  continues 
to  increase  take  off  the  load,  slow  down,  loosen  caps,  get  the  belt  off  as  soon  as 
possible,  keep  the  armature  moving  to  prevent  sticking,  take  off  the  caps,  then 
stop  the  revolving,  take  out  the  linings  and  allow  them  to  cool  in  the  air.  Do 
not  throw  them  into  water.  Scraping  the  linings  can  only  be  done  by  an 
experienced  person.  The  shaft  is  also  polished  with  crocus.  Do  not  use  ice  or 
water  to  cool  a  hot  box. 

Occasionally  hold  a  small  piece  of  clean  white  cotton  cloth — never  waste — on 
the  commutator  to  wipe  it  clean ;  then  put  on  two  or  three  drops  of  vaseline. 

Keep  printed  directions  and  diagrams  of  all  circuits  posted. 

STOPPING. 

4.  If  the  dynamo  is  alone  and  not  charging  a  battery  or  supplying  a  motor, 
slow  down  the  engine  to  a  few  revolutions ;  open  main  switch ;  raise  brushes 
if  copper ;  hold  clean  white  cloth  on  commutator  until  no  dirt  shows ;  stop  the 
engine ;  open  the  feeders  and  field  rheostat ;  feel  the  armature  winding  for  heat ; 
loose  the  belt. 

If  a  battery  is  being  charged,  reduce  the  charging  current  to  a  few  amperes 
and  open  the  battery  switch,  then  slow  down  the  engine  and  proceed  as  above. 
If  a  motor  is  being  supplied,  it  must  first  be  gradually  cut  out  by  its  rheostat. 

If  the  dynamo  is  working  in  parallel,  reduce  its  current  to  nearly  0  and  open 
its  switch  before  reducing  speed. 

To  prevent  mechanical  shock,  never  open  a  main  switch  carrying  more  than 
a  few  amperes  except  in  case  of  emergency. 

After  stopping,  dust  the  dynamo  and  clean  it  thoroughly  while  warm  with 
cotton  cloth — never  waste.  Remove  any  trace  of  oil  or  metallic  dust,  especially 
from  brush,  brush  holder,  or  commutator.  Every  part  is  kept  scrupulously 
clean.  A  bad  joint  or  a  loose  nut  is  detected.  Cover  the  machine.  The  room  is 
then  swept  and  dusted  and,  if  not  sunlighted,  a  lamp  is  maintained  to  keep  it  dry. 


V.— THE    SWITCHBOARD. 


(A)   ARRANGEMENT  AND   CONNECTIONS. 

1.  The  switchboard  is  the  electrical  center  of  an  installation.     Its  distributing, 
measuring,  regulating  and  protecting  apparatus  are  systematically  and  con- 
veniently arranged  on  the  front  of  one  or  more  slate  panels  held  in  a  metal 
frame.     On  the  back  the  bus  bars  and  all  copper  wires  connecting  the  apparatus 
are  accessible,  insulated,  rigid  and  straight  between  supports  except  where  they 
are  bent  out  1  inch  in  crossing 

Wires  running  from  the  switchboard  are  neatly  aligned  and  run  horizontally 
or  vertically  along  ceiling  and  walls  in  conduit  or  taut  between  large  porcelain 
insulators  on  asphalted  strips.  Connections  are  sweated  and  bolted ;  small  wires 
may  be  jointed  and  soldered.  As  a  rule,  the  drop  from  a  dynamo  post  to  any 
feeder  on  the  same  leg  is  less  than  one-fourth  of  1  per  cent.  Fig.  78  suggests 
the  entire  system  where  cells  are  charged  and  discharged  in  series. 

2.  The  switchboard  connections  should    permit  four  conditions — first,  the 
dynamo,  or  dynamos  in  parallel,  to  feed  directly  all  lamps,  motors,  searchlights, 
etc.,  or  any  part  of  them,  and  in  large  installations  to  leave  one  spare  unit  idle; 
second,  to  charge  the  battery  or  batteries  alone ;  third,  to  do  both  simultane- 
ously ;  fourth,  the  battery  to  supply  in  case  of  a  breakdown  to  the  machinery, 
all  current  to  the  circuits  of  its  emplacements  except  motors  and  searchlights. 

3.  There  will  then  be  one  generator  panel  or  board  of  panels  in  the  power 
room  centrally  located,  and  a  panel  for  each  battery  reserve  near  its  emplace- 
ment, but  not  in  the  same  room  with  the  battery.     If  there  is  only  one  battery 
and  the  dynamo  is  near  it,  the  two  panels  will  be  mounted  together  in  the 
dynamo  room. 

The  panel  is  of  best  slate,  1|  inches  thick,  held  vertically  2  feet  from  the  wall. 
1  foot  from  floor  by  a  metal  frame  from  which  it  is  insulated  by  ebonite  bush- 
ings and  washers.  The  dynamo  panel,  about  6£  by  2£  feet,  will,  when 
necessary,  be  mounted  with  others  like  it  in  a  continuous  board.  The  battery 
switchboard  is  about  <5£  by  3|  feet  wide  and  its  bus  bars  will  receive  their  supply 
either  from  a  dynamo  feeder  or  battery.  A  searchlight  must  have  its  own 
switchboard,  supplied  by  a  feeder  from  the  dynamo  board's  bus  bars. 

4.  The  simplest  and  best  form  of  switchboard  arrangement  affording,  with  the 
least  apparatus,  ample  control  and  protection  for  one  or  any  number  of  emplace- 
ments and  batteries,  is  given  for  both  generator  and  battery  panel  fronts  on 
page  74.     It  will  no  doubt  be  adopted  in  the  course  of  a  few  years.     For  a  single, 
compact  plant  the  arrangement  may  be  as  on  page  75. 

On  account  of  the  diversity  of  switchboards  which  will  be  met  with,  several 
diagrams  are  given  below. 

(B)   GENERAL  DESIGN. 

The  general  design  and  apparatus  ought  to  allow : 

Separate  feeders  from  dynamo  board  to  battery  panels,  motors  and  search- 
lights ;  from  each  battery  panel  to  its  centers  of  distribution. 

Such  regulations  that  all  centers  of  distribution  may  be  kept  at  the  same  poten- 
tial, all  batteries  may  have  their  normal  charging  and  discharging  currents,  and 
the  charging  of  two  battery  halves  may  be  equalized. 

Magnetic  protection  to  every  dynamo,  motor,  and  battery  against  overload  and 
underload. 

Measurements  of  C  and  V  of  any  part  desired  and  of  leakage. 

The  details  of  apparatus  are  given  in  figs.  79  and  80.  The  same  apparatus  is 
indicated  by  symbols  for  other  boards.  The  best  switchboard  arrangement 
to  be  found  in  forts  appears  on  pages  58,  59. 

1.  Weston  voltmeters,  V,  reading  to  150 ;  a  recording  volt  gauge  for  the  battery 
is  advisable. 

2.  Weston  shunt  ammeters,  A,  reading  to  one-half  excess  of  the  maximum 
current. 

(56) 


78.  W-e  Switch  Board  Front. 


56 


THE   SWITCHBOARD.  57 

3.  6-point  voltmeter  switch  on  battery  panel  connected  to  give  at  will  the 
voltage  (a)  between  bus  bars,  (b)  of  first  half  battery,  (c)  of  second  half  battery, 
(d)  of  whole  battery,  (e)  between  +  bar  and  ground,  (/)  between — bar  and  ground ; 
4-point  switch  on  dynamo  panel  to  give  the  voltage  (a)  between  supply  mains, 
(b)  bus  bars,  (c,  d)  either  bus  and  ground. 

4.  Main  regulating  rheostat  M  R  of  noncpmbustible,  nonabsorptive  material  is 
necessary  to  reduce  the  bus  bar  voltage  while  charging  the  battery.     It  has  range 
and  capacity  to  carry  indefinitely  with  less  than  200°  F.  rise,  the  charging  cur- 
rent of  both  battery  halves  within  5  per  cent  of  the  normal  while  the  bus  bars 
remain  at  112  volts ;  enough  stops  are  provided  to  keep  the  bus  bars  within  1  volt 
of  the  potential  necessary  to  supply  the  lamps. 

5.  Equalizing  rheostats,  E  R,  E  R,  have  each  ten  steps  for  a  total  drop  of  10 
volts,  and  in  construction  are  like  the  above. 

6.  The  field  rheostat,  F  R,  supplied  with  the  dynamo,  can  lower  its  maximum 
voltage  on  load  to  110. 

7.  All  rheostats  are  required  to  have : 

Capacity  to  carry  its  ma  :imum  current  indefinitely  with  less  than  200°  F.  rise, 
and  30  per  cent  overload  for  one  minute. 

Contact  arm  on  a  spindle  and  touching  one  point  before  it  leaves  the  other. 

All  material  fire  and  moisture  proof  and  conductor  nonoxidizable. 

Compactness,  ventilation,  and  abundant  radiating  surface. 

Insulation  of  1  megohm  between  conductor  and  frame  under  A.  C.  test. 

Words  "high,"  "low,"  or  "raise,"  "lower,"  to  indicate  the  turn  of  contact 
arm  to  change  the  voltage. 

8.  Its  overload  circuit  breakers,  O  L,  operate  with  certainty  and  excess  of  force 
within  5  per  cent  of  adjustment.     This  is  usually  made  to  open  automatically 
the  circuit  at  one-fourth  increase  of  the  normal  current. 

9.  Its  underload  C.  B's.  operate  within  5  per  cent  of  adjustment,  and  is  usually 
set  to  open  the  circuit  with  a  fall  of  5  or  10  amperes  if  the  C.  B.  is  "no  current," 
and  of  voltage  30  per  cent  if  the  underload  is  ' '  low  voltage. "    It  should  not 
catch  if  the  current  or  voltage  is  lower  than  that  of  the  adjustment.     Both  O  L 
and  U  L  circuit  breakers  have  carbon  protection  to  the  main  contacts,  and  if 
combined  on  one  base,  have  but  one  trip-catch. 

10.  Fuses  have  copper  tips  stamped  with  80  per  cent  of  the  amperes  which 
they  can  carry  indefinitely,  and  will  therefore  blow  at  one-fourth  excess  of  their 
normal  current. 

11.  Knife  switches  are  50  amperes  or  larger,  double  pole,  single  or  double 
throw,  quick  break,  fused,  carbon -tipped,  hinged,  and  so  constructed  that  con- 
tact will  occur  along  the  entire  edge  of  the  jaw  at  the  same  time,  and  no  current 
can  pass  through  a  hinge  or  spring.     Single-throw  are  closed  by  an  upward 
motion  to  avoid  accidental  closing. 

12.  All  conducting  parts  of  the  switch  board  are  of  drawn  copper  and  have  a 
cross  section  of  about  1  square  inch  per  400  amperes;  all  joints  are  sweated  and 
bolted  with  a  contact  area  of  1  square  inch  per  180  amperes;  all  sliding  contact 
surfaces  have  1  square  inch  per  40  amperes.     Bearing  parts  are  phosphor-bronze 
or  brass. 

(C)  THE  U.  S.  ENGINEER  SWITCHBOARD. 

1.  Figs.  79  and  80  give  the  details  of  apparatus  and  wiring  of  the  dynamo 

and  battery  panels.     The  feeders, \-  to  the  latter,  come  from  F  S  off  the 

dynamo  panel's  bus  bars. 

Fig.  81  shows  the  connections  on  the  battery  switchboard  panel  (fig.  80),  while 
the  storage  battery  is  being  charged,  and  fig.  82  while  being  discharged..  The 
three  figures  are  lettered  to  correspond. 

2.  By  this  arrangement,  the  battery  of  58  cells  is  charged,  29  in  series  and  2  in 
parallel,  by  the  throw  of  the  triple -pole  double -throw  switch,  T  P  D  T,  on  the 
battery  panel  to  the  right  and  is  discharged,  58  in  series,  by  its  throw  to  the  left. 
The  plar  allows  other  and  distant  batteries,  each  with  its  own  switch  board,  to 
be  supplied  by  feeders  from  the  same  dynamo  board's  bus  bars,  permits  the 
dynamo  to  feed  all  lamps,  etc. ,  at  the  same  potential,  offers  little  chance  for 
mistakes  or  accident  and  fulfills  the  four  conditions  imposed  in  par.  (A)  2,  for 
isolated  D.  C.  plants  with  battery  reserves.     But  the  apparatus  is  extensive  and 
current  is  lost  in  dead  resistance  while  charging  and  lighting  at  the  same  time. 

3.  Details  of  the  apparatus : 

(a)  In  the  Weston  voltmeter  V,  (fig.  79)  a  pivoted  coil,  of  which  only  three 
turns  are  shown  in  cross  section,  is  held  in  position  between  the  poles  JVand  S  of 
a  strong  steel  magnet  by  a  light  spiral  watch  spring  F,  seen  in  front,  and  one,  R, 


58 


HANDBOOK   FOR   ELECTRICIANS. 


79.  Present  Generator  Panel  Apparatus  in  Detail. 


THE    SWITCHBOARD. 


59 


80.  Engineer  Battery  Panel. 


60 


HANDBOOK   FOK   ELECTRICIANS. 


like  it,  in  rear,  but  drawn  on  the  left  in  order  to  be  seen.  When  a  current  passes 
through  the  coil,  it  revolves  on  its  pivots  on  the  same  principle  as  the  armature 
of  a  motor  and  carrying  with  it  the  pointer  along  the  scale.  The  V  coil  has 
many  turns  of  very  fine  wire  and  a  large  fixed  resistance  in  series,  which  is  kept 
in  the  instrument  case. 


81  and  82.  Diagrammatic  Sketch  of  Engineer  Switchboard  Battery  Panel. 

(&)  The  Weston  ammeter  A  is  similarly  constructed,  but  has  fewer  turns  of 
coarser  wire  in  the  coil,  which  carries  a  very  small  but  a  fixed  fraction  of  the  main 
current  through  the  shunt  A  S  of  German-silver  strips  in  the  main  circuit. 
Ammeters  and  voltmeters  are  inclosed  in  iron  cases  to  shield  their  fields,  and 
they  should  be  handled  with  care,  so  as  not  to  disturb  the  pivots  or  weaken  -the 
magnets. 

(c)  The  voltmeter  switch  V  S  has  two  brass  arcs  which  are  the  terminals  of 
the  V circuit;  also  (fig.  79),  four  double  brass  points  connected  as  shown.  The 


83.  G.  E.,  D.  P.  Overload  Toggle-Joint  C.  B.. 


THE    SWITCHBOARD. 


61 


brass  ends  of  the  lever  (not  shown)  are  insulated  from  each  other  and  bear  upon 
the  arcs  and  two  opposite  points  at  the  same  time.  The  voltmeter  can  thus  be 
switched  in  between  (1)  dynamo  posts,  (2)  bus  bars,  (3)  —  bus  bar  and  ground, 
or  (4)  +  bus  bar  and  ground.  The  V  S 
on  dynamo  panel  has  six  points. 

(c?)  In  the  overload  switch  O  L  the 
knife  edge  kept  open  by  a  spring  is, 
when  pushed  into  the  jaws  by  its  han- 
dle (thus  closing  the  circuit),  held  in 
that  position  by  a  trigger  catch.  Be- 
neath the  catch  and  on  the  other  side  of 
its  pivot  is  a  plunger  H  over  a  vertical 
soft-iron  movable  core  I  (fig.  84),  sur- 
rounded at  its  upper  end  by  a  coil  car- 
rying the  main  current.  When  the 
current  becomes  too  great  the  core  is 
drawn  up,  strikes  the  plunger  and  catch 
and  releases  the  knife.  The  spring  over- 
comes the  friction  of  the  jaw  on  the 
knife  which  then  opens  the  circuit  far 
more  quickly  and  surely  than  is  done  by 
a  fuse  wire.  The  hand-screw  shown 
below  7,  which  moves  the  core  up  or 
down,  affords  regulation. 

The  figure  (85)  gives  back  connections 
of  Ite  C.  B.  and  protected  terminal  fuse. 

(e)  O  L  and  U  L  (fig.  79)  is  a  combina- 
tion overload  and  underload  automatic 
circuit  breaker.  In  addition  to  the  over- 
load cut-out,  described  above,  there  is  a 
straight  horizontal  magnet  with  end 
pole  pieces.  It  may  be  wound  with  fine 
wire  connected  for  a  fall  in  voltage  as 
represented  in  the  diagram,  or  with 
coarse  wire  in  series  with  the  OL  coil  84>  ite  Automatic  Cut=out  or  Circuit  Breaker. 
to  open  for  a  fall  in  current.  The  arma- 
ture is  a  horizontal  soft-iron  cross  piece  at  the  upper  extremity  of  a  vertical  lever 
pivoted  below  and  held  by  a  spring  normally  away  from  the  magnet.  When 


Diagram  No.  1. 


Diagram  No.  2. 


85. 


the  knife  of  the  switch  is  closed  by  the  handle,  the  armature  is  automatically 
moved  into  approximate  contact  with  the  pole  pieces  and  held  by  their  magnet- 
ism. If  the  voltage  falls  to  the  adjustment,  the  armature  lever  is  released  and 
strikes  the  trigger  catch,  releases  the  knife  and  opens  the  main  circuit. 


HANDBOOK   FOR   ELECTRICIANS. 


THE  PRESIDE  SWITCHBOARD 

(Fig.  86),  for  a  single  plant  with  a  battery  reserve,  requires  little  apparatus, 
loses  very  little  energy  in  regulation,  gives  little  chance  for  accident,  and  it  is 
simple.  Lamps  are  110  volt;  dynamo,  110  to  150  volts;  58  cells  charged  and  dis- 
charged in  series  vary  from  110  to  145  volts.  1.  Dynamo  to  light  lamps — close 
O  L,  M  S,  and  F  S  only ;  M  R  is  cut  out.  2.  Dynamo  to  charge  battery — close 
T  P  D  T  to  right,  O  L,  O'  L',  U  L,  and  M  S  only.  3.  Dynamo  to  do  both— same 
as  last  and  close  F  S.  4.  Battery  to  light  lamps— close  O  L',  T  P  D  T  to  left 
and  F  S, 


JL 
JL 

T 
T 

FS 

FS 

LJ                   rj 

1                       1                            1 

86.  Preble  Switchboard. 


(E)  KEY  WEST  SWITCHBOARD. 

The  relative  sizes  of  wires,  fuses,  switches,  etc.,  and  the  divided  bus  bars  are 
shown  in  fig.  87.  A  shunt  switch  on  the  dynamo  to  the  series  field  may  be  opened 
to  raise  the  voltage. 

The  ten  end  cells,  active  or  npnactive,  may  be  gradually  added  or  subtracted 
from  the  main  battery,  as  required,  by  an  end  cell  switch.  Its  arm  consists  of 
two  parallel  brass  bars  sliding  on  the  stops  and  on  two  different  brass  rings  con- 
nected by  German -silver  resistance.  By  this  device  the  battery  circuit  is  never 
opened  and  no  cell  can  be  short-circuited 


87.  Key  West  Switchboard. 


THE  SWITCHBOARD. 


63 


(F)  THE  GOLDEN  GATE  BOARD. 

The  Golden  Gate  board  (fig.  88)  distributes  current  to  three  points,  1,500  and 
2,000  feet  apart,  each  having  its  own  battery  for  a  reserve.  The  generator  and 
No.  2  stations  are  together.  Battery  and  lamps  can  be  supplied  simultaneously, 
but  not  battery  and  motors. 


88.  Golden  Gate  Switchboard. 
(G)  SWITCHBOARD  ARRANGEMENT. 

The  switchboard  arrangement  in  fig.  89  for  dynamo,  single  battery,  with  15 
end  active  cells  and  100  lamps,  is  economical.  It  fulfills  the  four  conditions  and 
the  dynamo  and  battery  can  be  placed  in  parallel  to  supply  400  lamps  for  three 
hours. 


89.  Shunt  Dynamo,  45  Cells  and  15  Active  End  Cells. 


64  HANDBOOK    FOR    ELECTRICIANS. 

(H)  TO  OPERATE. 

1.  No  one  should  be  allowed  to  touch  the  switchboard  unless  he  is  familiar 
with  all  circuits  connected  with  it,  the  strength  of  main  and  feeder  circuits, 
the  insulation  of  each  part.     Records  of  these  are  kept. 

2.  Always  close  a  switch  deliberately  and  firmly,  while  watching  the  ammeter 
and  voltmeter,  whose  deflections  were  previously  known,  and  while  standing 
ready  to  open.     Main  switches  loaded  are  opened  only  in  an  emergency. 

3.  The  rule  is  to  close  feeder  switches  when  practicable,  so  as  to  change  the 
load  as  gradually  as  possible — the  smaller  first. 

4.  Guard  against  dust  or  wet,  overheating  in  any  part,  unsoldered  joints, 
loose  nuts,  wires  or  other  parts,  bad  contact  of  rheostat  arm  on  any  stop,  instru- 
ment not  holding  its  zero,  switch  twisted  or  dirtied  so  as  to  not  make  good  con- 
tacts ;  apparatus  out  of  adjustment. 

5.  Leave  all  switches  and  circuit  breakers  open  after  a  run. 


OF  THE 

UNIVERSITY 

OF 


90.  As  Shipped  and  Prepared  for  Mounting. 


VI.— STORAGE  BATTERY  (CHLORIDE). 


(A)  UNPACKING,   SETTING  UP,  AND  INITIAL   CHARGING. 

1.  Great  care  should  be  taken  in  unpacking  and  all  subsequent  handling. 

2.  Open  boxes  and  crates  on  the  "up  "side.     Lift  contents  out,  verify  their 
number  and  condition,  and  never  slide  them  by  turning  box  on  its  side. 

3.  The  construction  of  the  stand  is  shown  in  fig.  91.     Dimensions  change 
with  size  of  jar.     When  jars  are  15  inches  high  by  13  inches  wide  by  11 
inches  deep,  the  cross  section  of  the  timbers  are  5|  inches  deep  by  3f  inches 
wide.     When  each  shelf  carries  two  rows  of  cells,  there  will  be  four  longitudinal 
stringers  to  each  shelf  instead  of  two  stringers,  as  shown  for  the  single  row 
of  cells. 

4.  The  battery  room  should  be  so  located  or  arranged  that  the  temperature 
will  be  moderate  and  the  air  dry.     If  the  room  is  damp  there  is  danger  of  leak- 
age from  grounds  and  solution  running  over  from  absorption. 

5.  Usually,  natural  ventilation  is  sufficient  if  the  proper  inlets  and  outlets 
for  the  air  have  been  provided,  but  in  some  cases  forced  draft  is  necessary.     To 
obtain  the  best  results  and  life  from  the  battery,  the  temperature  should  be 


91.  Method  of  Mounting.    Working  Plan  of  Frame. 


Glass  jar. 
Wood  tray. 
Glass  insulator. 
Stringer. 
Iron  bolt. 


F     Crosspiece. 


G  Wood  dowel  pin.  L 

H  Post.  M 

I  Lead-covered  bolt  connector.  N 

J  Lead  strap  lug.  0 

K  Positive  plate.  P 


Negative  plate. 

Rubber  ring  separator. 

Vitrified  brick. 

Lead  terminal  lug. 

Copper  connecting  conductor. 


between  50°  and  80°  F.  If  the  room  is  excessively  hot  (over  80°)  for  any  great 
length  of  time,  the  life  of  the  plates  is  very  considerably  shortened.  If  the 
temperature  is  low,  no  harm  results,  but  the  available  capacity  is  reduced. 

6.  Place  the  jars,  after  they  have  been  cleaned,  in  position  on  the  stands 
which  should  be  so  situated  in  the  room  that  each  cell  will  be  easily  accessible. 
If  the  floor  space  is  available,  it  is  often  preferable  to  install  the  cells  on  one 
tier,   in  which  case  a  set  of  stringers  properly   fastened  together  and  the 
insulating  bricks  will  be  all  that  is  required. 

7.  Place  the  elements  as  they  come  from  the  packing  cases  (see  fig.  90)  on 
a  convenient  stand  or  table  (the  elements  are  packed  positive  and  negative 
together,  the  positive  having  plates  of  a  brownish  color,  the  negative  of  a  light 

1714-5  (65) 


66  HANDBOOK   FOR   ELECTRICIANS. 

gray ;  the  negative  always  has  one  more  plate  than  the  positive) ,  cut  the  strings 
that  bind  them  together  and  carefully  pull  the  positive  and  negative  groups 
apart,  throwing  the  packing  aside.  After  carefully  looking -over  both  elements, 
to  see  that  they  are  free  from  dirt  and  other1  foreign  matter,  place  two  hard 
rubber  separators  on  each  positive  plate,  about  an  inch  from  and  parallel  with 
each  vertical  edge,  and  then  slip  these  plates  into  position  between  the  nega- 
tives, which  have  been  placed  crosswise  on  a  board  about  two-thirds  the  width 
of  the  plates,  so  as  to  allow  of  easy  readjustment  of  the  separators,  which  may 
become  disarranged  (fig.  91). 

8.  To  facilitate  the  lifting  of  the  elements  into  the  jars  and  to  prevent  the 
disarrangement  of  the  separators  when  doing  this,  a  short  strip  of  webbing 
should  be  used;  lay  this  on  the  board  under  the  element   (fig.  90).     When 
putting  into  the  jars,  be  careful  that  the  direction  of  the  lugs  is  relatively  the 
same  in  each  case,  thus  causing  a  positive  lug  of  one  cell  to  always  connect 
with  a  negative  of  the  adjoining  one  and  vice  versa.     This  insures  the  proper 
polarity  throughout  the  battery,  bringing  a  positive  lug  at  one  free  end  and  a 
negative  at  the  other. 

9.  Just  before  bolting  or  clamping  the  lugs  together,  they  should  be  well 
scraped  at  the  points  of  contact,  to  insure  good  conductivity  and  low  resistance 
of  the  circuit;  this  should  be  done  before  the  elements  are  taken  apart  and 
directly  after  unpacking,  if  the  battery  is  to  be  set  up  at  once.     The  jars  rest  on 
sand  in  wooden  trays  on  glass  insulators  standing  on  framework  as  shown 
above. 

10.  Before  putting  the  electrolyte  into  the  cells,  the  circuits  connecting  the 
battery  with  the  charging  source  must  be  complete,  care  being  taken  to  have 
the  positive  pole  of  the  charging  source  connected  with  the  positive  end  of  the 
battery,  and  so  with  the  negative  poles. 

11.  The  electrolyte  is  dilute  sulphuric  acid  of  a  specific  gravity  of  1.200  or  25° 
Baume  as  shown  on  the  hydrometer  at  normal  temperature  (60°  F).     If  it  is 
not  convenient  to  procure  this  from  the  Battery  Company,  already  mixed  and 
ready  for  use,  it  should  be  prepared  by  diluting  suitable  commercial  sulphuric 
acid,  or  "oil  of  vitriol,"  as  it  is  more  commonly  called,  with  pure  water.     The 
acid,  as  well  as  the  water,  must  be  free  from  impurities,  such  as  iron,  arsenic, 
nitric  or  hydrochloric  acid;  this  is  absolutely  essential.     When  diluting,  the 
acid  must  be  poured  into  the  water,  not  the  water  into  the  acid ;  the  propor- 
tions of  acid  (of  1.840  specific  gravity  or  66°  Baume)  and  water  are  one  part  of 
acid  to  five  of  water  (by  volume).     The  acid  must  be  added  to  the  water  slowly 
and  with  great  caution,  on  account  of  the  heat  generated ;  the  final  density  of 
the  solution  (1.200  specific  gravity)  must  be  read  when  the  solution  has  cooled. 
The  vessel  used  for  the  mixing  must  he  a  lead-lined  tank,  glazed  earthenware 
or  one  of  wood  which  has  not  been  used  for  other  purposes ;  a  new  washtub  or 
spirits  barrel  is  recommended. 

12.  The  electrolyte  should  cover  the  top  of  the  plates  by  i  inch  and  must  be 
cool  when  poured  into  the  cells,  which  then  should  never  be  allowed  to  stand 
for  more  than  two  hours,  before  the  charging  is  started. 

13.  The  initial  charge  should  be  continued  uninterruptedly,  or  as  nearly  so  as 
possible,  for  about  thirty  hours  at  normal  rate,  or  until  the  positive  plates 
become  a  deep  brown  or  chocolate  color,  the  negative  a  light  slate  and  the 
potential  of  each  cell  2.5  volts  (with  current  flowing),  gas  being  freely  given  off 
from  all  the  plates.     The  density  of  the  electrolyte  should  again  be  1.200  sp.  gr., 
having  fallen  considerably  after  being  put  in  the  jars. 

14.  At  the  end  of  the  first  charge,  it  is  well  to  discharge  the  battery  about  | ; 
and  then  immediately  recharge  it.     Repeat  this  treatment  two  or  three  times 
and  the  battery  will  be  in  proper  working  condition. 

15.  When  the  battery  is  in  regular  service,  the  discharge  should  not  be  car- 
ried below  1.8  volts  per  cell  at  full  load;  the  charging  should  be  started  at  once 
after  a  discharge  and  continued  until  the  battery  is  full,  as  indicated  by  the 
four  signs  given  above,  i.  e.,  potential,  specific  gravity,  color,  and  gassing,  the 
first  two  being  most  important.     The  cells  must  never  be  allowed  to  stand  dis- 
charged.    If,  by  chance,  this  should  happen,  then  the  charging  must  be  pro- 
ceeded with  at  half  rate ;  the  potential  in  this  case  at  the  end  of  charge  should 
be  2.4  volts  (0.1  volt  less  than  normal)  and  the  density  of  the  electrolyte  1.200 
sp.  gr. ,  the  same  as  when  the  charge  is  at  normal  rate.     Upon  discontinuing  a 
charge  the  potential  of  each  cell  will  immediately  fall  to  about  2.2  volts,  and 
then  to  2  volts  when  the  discharge  is  started. 

16  In  order  to  determine  whether  the  battery  continues  in  good  condition,  it 
is  essential  that  potential  and  density  readings  be  taken  at  least  once  a  week 
just  before  beginning  the  charge  and  also  near  the  end. 


STORAGE   BATTERY. 


67 


(B)  GENERAL.  INSTRUCTIONS  FOR  CARE  AND  OPERATION 
OF  CHLORIDE  STORAGE  BATTERY. 

To  obtain  the  best  results  in  the  operation  of  the  battery,  it  is  absolutely  essen- 
tial that  proper,  careful,  and  methodical  attention  be  given  to  all  the  details  of 
its  operation,  the  same  as  is  necessary  with  the  generating  machinery,  and  for 
tliis  reason  the  following  information  and  rules  should  be  most  carefully  noted 
and  followed ;  if  this  is  done  the  total  work  in  connection  with  the  operation  of 
the  battery  will  be  reduced  to  a  minimum : 

1.  Charging. — In  the  charging  of  the  battery,  which  should  preferably  be  at 
the  normal  rate,  it  is  most  important  that  it  be  continued  until  complete,  but  it 
is  equally  as  important  that  it  should  not  be  repeatedly  continued  beyond  that 

point,  as  not  only  will  an  unnecessarily  rapid 
accumulation  of  sediment  and  excessive  evapo- 
ration of  the  electrolyte  result,  but  what  is  more 
important,  the  life  of  the  plates  will  be  very 
much  shortened. 

At  weekly  intervals,  however,  it  is  advisable 
to  slightly  prolong  the  charge,  in  order  that  the 
electrolyte  may  be  thoroughly  stirred  up  by  the 
prolonged  gassing,  and  also  to  correct  any  un- 
evenness  in  the  working  of  the  cells,  which  may 
have  developed. 

2.  A  complete  charge  which  in  general  should 
exceed  the  previous  discharge  by  from  12  to  15 
per  cent  (in  ampere  hours)  is  determined  by  the 
voltage  and  specific  gravity  of  the  electrolyte  or 
solution  in  the  cells  reaching  a  maximum  (not 
necessarily  a  fixed  value),  also  by  the  amount  of 
gassing,  and  by  the  color  of  the  plates,  the  first 
two  being  the  chief  guides. 

3.  Determination  of  maximum   voltage  and 
specific  gravity. — With  all  of  the  cells  in  the 
battery  in  normal  condition,  with  no  impurities 
in  the  electrolyte  and  no  material  lodged  between 
the  plates  or  sediment  touching  them  at  the  bot- 
tom, the  maximum  voltage  and  maximum  specific 
gravity  of  the  electrolyte  is  reached,  when,  with 


92.  Type  E=ll  in  Glass  Jar. 


the  charging  current  constant  at  the  normal  rate,  no  further  rise  or  increase  in 
either  (voltage  or  specific  gravity)  during  a  period  of  one-half  hour  is  noted. 
For  instance,  if  the  charge  has  been  continued  for  five  hours  with  a  gradual 
continued  rise  in  the  voltage  and  specific  gravity  during  that  time,  but  with  an 
additional  one -half  hour  of  charging  there  is  no  further  rise  in  either,  then  the 
charge  is  to  be  considered  complete. 

If  the  charging  is  at  a  rate  lower  than  the  normal,  the  interval  during  which 
no  perceptible  rise  should  occur  must  be  proportionately  increased. 

4.  TJie  voltage  at  end  of  charge  is  not  always  the  same  throughout  the  life  of 
a  battery,  being  dependent  chiefly  upon  two  conditions,  namely :  the  age  of  the 
battery  and  the  temperature  of  the  electrolyte,  and  for  this  reason  it  is  most 
important  in  determining  the  completion  of  a  charge,  that  these  conditions  be 
taken  into  consideration. 

When  first  installed,  the  end  of  charge  voltage  will  be  2. 5  volts  per  cell,  or 
higher,  at  normal  rate  and  at  normal  temperature  (70°  F.),  but  as  the  age  of  the 
battery  increases  the  point  at  which  it  will  be  fully  charged  is  gradually  lowered 
for  corresponding  rates  and  temperatures  (see  below)  until,  in  many  cases,  with 
both  normal,  it  will  have  fallen  to  2.40  volts,  or  even  less,  per  cell. 

If  the  charging  current  is  at  the  maximum  rate,  which  should  never  be  used 
except  in  cases  of  emergency,  where  a  rapid  charge  is  necessary,  the  final 
voltage  will  be  approximately  0.05  volt  per  cell  above  that  of  the  normal  rate. 

With  rates  lower  than  the  normal,  the  voltage  at  end  of  charge  will  be  approx- 
imately 0.05  volt  less  for  each  one-fourth  decrease  in  the  rate,  viz: 

If  2.50  volts  at  normal  rate  (100  amperes  for  illustration),  then  2.45  volts  at 
three-fourths  normal  rate  (75  amperes  for  illustration),  and  2.40  volts  atone- 
half  normal  rate  (50  amperes  for  illustration). 

The  effect  of  changes  in  temperature  on  the  final  charging  voltage  is  that  it 
is  noticeably  lowered  with  an  increase  in  the  temperature  above  the  normal 
(70°)  and  correspondingly  increased  with  lowered  temperatures,  irrespective  of 
the  age  of  the  battery. 


68  HANDBOOK   FOR   ELECTRICIANS. 

5.  Voltage  after  charge  and  before  discharge. — After  the  completion  of  a 
charge  and  the  current  is  off,  the  voltage  per  cell  will  fall  immediately  to  about 
2.15  volts,  and  then  to  2.00  volts  when  the  discharge  is  started.     If  this  is  not 
begun  at  once,  then  the  pressure  will  quite  rapidly  fall  to  2. 05  volts,  and  there 
remain  while  the  battery  continues  on  open  circuit. 

6.  Specific  gravity  of  electrolyte  at  end  of  charge  and  conditions  affecting 
it. — As  with  the  voltage,  the  specific  gravity  for  complete  charge  is  also  affected 
more  or  less  by  the  varying  conditions  during  the  progress  of  the  life  of  the 
battery,  in  addition  to  the  changes  due  to  the  evaporation  and  replacing  of  the 
water  in  the  solution — the  sulphuric  acid  not  evaporating. 

In  the  beginning  it  should  be  between  1.195  and  1.205  sp.  gr.,  at  normal 
temperature,  and  with  the  solution  at  the  proper  height  (f  inch)  above  the  top  of 
the  plates. 

Gradually  there  is  a  slight  loss  of  the  acid  from  the  electrolyte,  through  very 
small  quantities  being  carried  off  in  that  portion  of  the  minutely  divided  spray 
that  is  thrown  up  during  gassing  at  end  of  charge,  which  is  prevented  from 
falling  back  into  the  cell  by  the  air  currents  in  the  room.  In  addition,  some  of 
it  is  absorbed  by  and  acts  upon  the  sediment  which  slowly  accumulates  in  the 
bottom  of  the  tanks,  and  so  can  not  go  back  into  the  solution  again. 

7.  Restoring  lowered  specific  gravity. — When  this  loss  has  become  such  that 
the  highest  reading  that  can  be  gotten  at  end  of  complete  charge,  all  indi- 
cations of  such  being  present,  is  ten  points  below  the  standard  or  what  it  was 
when  first  put  into  regular  service,  i.  e.,  if  it  has  fallen  from  1.200  sp.  gr.,  the 
original  reading,  to  1.190  sp.  gr.,  then  this  loss  should  be  regained  by  the  addi- 
tion of  dilute  acid  instead  of  water,  when  replacing  evaporation.     Under  ordi- 
nary conditions  it  should  not  be  necessary  to  add  fresh  acid  oftener  than  once 
every  two  years,  or  possibly  only  at  such  times  as  the  sediment  is  removed.     A 
convenient  density  for  this  purpose  is  1.400°  sp.  gr.,  because  the  proper  density 
of  the  electrolyte  will  be  more  quickly  and  easily  attained  by  the  use  of  this 
heavier  solution,  it  containing  double  the  amount  of  pure  acid,  in  comparison 
with  that  of  1.200,  so  that,  for  instance,  if  four  carboys  holding  ten  gallons 
each,  of  1.200  sp.  gr.  solution,  would  be  required  in  any  particular  case,  the 
same  result  could  be  gotten  by  using  two  carboys  holding  ten  gallons  each,  of 
1.400  sp.  gr. 

As  it  is  essential  for  the  successful  operation  of  the  battery  that  the  electro- 
lyte be  free  from  impurities  (see  under  "Electrolyte"  below)  and  as  the  ordi- 
nary commercial  sulphuric  acid  is  not  of  the  proper  degree  of  purity,  it  is  very 
strongly  recommended  that  all  solution  be  purchased  through  the  Storage 
Battery  Company,  which  will  undertake  to  supply  the  proper  quality. 

If,  for  any  reason,  the  required  supply  is  not  procured,  the  solution  may  be 
prepared  by  diluting  specially  treated  sulphuric  acid,  or  oil  of  vitriol  as  it  is 
more  commonly  called,  with  pure  water. 

In  any  case,  a  carefully  collected  sample  (at  least  8  ounces)  should  be  sub- 
mitted for  test.  For  water  analysis  one  quart  is  required. 

8.  Gassing   and   color  of  plates — Additional  indications  of  state   of  charg- 
ing.— At  the  end  of  complete  charge,  in  addition  to  the  voltage  and  specific 
gravity  reaching  a  maximum,  gas  will  be  given  off  freely  from  all  of  the  plates  in 
the  battery,  and  the  color  of  the  plates  should  be  a  deep  chocolate  or  dark  brown 
for  the  body  of  the  positives  and  a  uniformly  light  slate  or  gray  for  the  nega- 
tives.    Provided  the  body  of  the  positive  plates  is  of  the  proper  color,  no  atten- 
tion need  be  paid  to  the  lodgment  on  the  top  of  these  plates  or  their  projecting 
buttons,  of  a  fine  white  powder  that  may  be  easily  brushed  off,  the  dark  color 
then  showing  underneath.     In  fact,  if  these  parts  are  of  the  deep  chocolate  color 
and  no  white  powder  is  noticeable,  it  is  an  indication  that  the  battery  is  being 
overcharged. 

This  white  powder  is  composed  of  particles  from  the  plates,  thrown  off  by  the 
gassing  at  end  of  charge,  which  become  sulphated  and  of  a  light  color  while  in 
suspension  in  the  electrolyte. 

9.  If  there  are  end  cells  in  the  battery,  i.  e.,  if  some  of  the  cells  are  so  con- 
nected with  the  switchboard,  that  by  either  cutting  them  in  or  out,  the  pressure 
can  be  regulated,  those  that  may  have  been  successively  cut  into  circuit  on  the 
discharge,  should  be  cut  out  again  on  the  following  charge,  as  soon  as  they  come 
up  to  a  state  of  full  charge  and  not  be  allowed  to  continually  overcharge.     If 
any  of  these  cells  are  not  used  regularly  or  stand  idle,  they  should  be  given  a 
complete  charge  once  a  week. 

10.  Counter  electromotive-force  cells. — In  some  of  the  smaller  plants  it  is  at 
times  more  suitable  to  provide  for  the  adjustment  of  the  pressure  by  means  of 


STORAGE    BATTERY. 


69 


what  are  known  as  counter  electromotive -force  cells,  instead  of  connecting  a 
number  of  the  cells  of  the  battery  to  the  regulating  switch  on  the  board.  These 
cells  are  made  up  of  plain  grids  or  plates  without  active  material  (storage 
capacity  not  being  required),  and  do  not  receive  any  of  the  charging  current, 
nor  do  they  require  the  careful  attention  that  end  cells  do.  They  should,  how- 
ever, be  examined  from  time  to  time,  to  see  that  they  are  not  short-circuited,  and 
if  found  so,  the  cause  should  be  removed,  the  same  as  in  the  case  of  the  regular 
cells  in  the  battery. 

11.  Discharge. — As  from  the  voltage  and  specific  gravity  readings  the  degree 
of  charge  can  be  determined,  so  likewise  can  the  amount  of  discharge. 

12.  Drop   in  voltage  and  specific  gravity  indication  of  amount  and  safe 
limit. — During  the  greater  part  of  a  complete  discharge  the  drop  in  voltage  is 
slight  and  very  gradual,  becoming  greater  with  marked  rapidity  near  the  end. 

The  limit  of  discharge  is  reached  when  the  voltage  has  fallen  to  1.75  volts  per 
cell  with  current  flowing  at  ordinary  rates ;  in  usual  service,  however,  it  is 
advisable  to  stop  the  discharge  considerably  above  this  point,  more  especially  to 
insure  a  reserve  in  case  of  emergency.  The  fall  in  density  of  the  electrolyte  also 
serves  as  an  indication  of  the  amount  taken  out,  and  is  in  direct  proportion  to 
the  ampere  hours  discharged,  thereby  differing  from  the  drop  in  voltage,  which 
varies  irregularly  for  different  rates  and  degrees  of  dis- 
charge, and  for  this  reason,  under  ordinary  conditions,  is 
to  be  preferred  in  determining  the  amount  of  discharge. 

The  actual  amount  of  the  variation  in  the  strength  of 
the  electrolyte  between  a  condition  of  full  charge  and  of 
complete  discharge  is  dependent  upon  the  quantity  of 
solution  in  the  containing  vessel,  compared  to  the  bulk 
of  the  plates. 

If  a  cell  contains  the  full  number  of  plates,  the  range 
will  be  about  35  points,  or  from  1.200  sp.  gr.  down  to 
1. 165  sp.  gr.  With  fewer  plates,  in  the  same  size  contain- 
ing vessel,  the  range  will  be  about  proportionately  lessened. 

13.  The  color  of  the  plates  is  also  a  guide,  as  it  is  when 
charging. 

As  the  discharge  progresses,  the  positive  plates  become 
lighter,  and  the  negatives  darker. 

14.  Interval  between  discharge  and  charge. — When  a 
battery  is  discharged  it  should  be  allowed  to  stand  but  a 
very  short  time  (not  more  than  an  hour),  if  at  all,  before 
beginning  charging  again. 

15.  Instruments  for  use  with    the   battery. — For    the 
successful  operation  of  the  battery,  there  should  be  pro- 
vided a  portable  low-reading  voltmeter,  reading  to  three 
volts  and  calibrated  to  0.02  volt,  for  taking  the  individual 
cell  readings ;  two  or  more  hydrometers,  with  scale  read- 
ing from  1.150  up  to  1.250  sp.  gr.,  and  a  portable  lamp 
for  inspecting  the  individual  cells,   in  addition  to  the 
switchboard  instruments,  consisting  of  a  voltmeter  read- 
ing approximately  three  times  the  number  of  cells  in 
series  in  the  battery,  a  two-way  ammeter  and  a  recording 
voltmeter  with  a  scale  that  will  clearly  show  the  total 
range  in  voltage  for  both  charge  and  discharge,  of  the 
cells  usually  in  circuit  on  the  discharge. 

The  recording  voltmeter  is  especially  desirable,  because 
it  enables  the  attendant  to  easily  and  accurately  note  the 
progress  of  charge  and  discharge,  and  determine,  in  con- 
junction with  the  hydrometer  readings,  after  the  manner 
noted  above,  the  proper  time  to  stop  either. 

In  addition  to  being  a  guide  for  the  charge  and  dis- 
charge, it  furnishes  a  permanent  record  of  the  working 
of  the  battery. 

An  ampere  hour  meter,  for  recording  the  amount  of 
both  the  charge  and  discharge,  is  also  valuable,  and  will  act  as  a  check  on  the 
readings  taken  with  the  other  instruments. 

16.  The  electrolyte  is  dilute  sulphuric  acid,  and  should  be  prepared  by  mixing 
suitable  commercial  sulphuric  acid  with  pure  water.     It  is  absolutely  essential 
that  both  acid  and  water  should  be  free  from  impurities  such  as  iron,  arsenic, 
nitric  acid  or  hydrochloric  acid. 


93.  Long  Flat  Hy= 
drometer. 


70  HANDBOOK   FOR   ELECTRICIANS. 

If  the  user  mixes  his  own  solution,  care  must  be  taken  to  pour  the  acid 
into  the  water,  not  the  water  into  the  acid.  The  acid  must  be  added  to  the 
water  slowly  and  with  great  caution,  because  of  the  heat  generated ;  the  final 
density  of  the  sojution  must  be  read  when  the  solution  has  cooled. 

The  proportions  of  acid  (of  1.840  sp.  gr.,  or  66°  Baume)  and  water  are  one 
part  of  the  former  to  five  of  the  latter  (by  volume).  The  vessel  used  for  the 
mixing  must  be  a  lead-lined  tank,  one  of  glazed  earthenware,  or  one  of  wood 
which  has  not  been  used  for  other  purposes. 

The  water  used  in  replacing  evaporation  should  be  of  the  best  quality.  If  it 
is  natural  water,  drawn  from  the  city  or  town  supply  or  other  source,  it  should 
be  submitted  from  time  to  time  for  test. 

The  water  should  be  added  to  the  top  of  the  cells  shortly  after  starting  the 
charge ;  not  after  finishing  a  charge  or  during  discharge.  Do  not  insert  a  hose 
into  the  cell  with  the  idea  of  stirring  up  the  electrolyte ;  this  may  result  in 
piling  up  the  sediment,  and  so  short-circuiting  the  plates. 

The  electrolyte  must  never  be  allowed  to  get  below  the  tops  of  the  plate. 

Should  it  be  known  that  any  impurity  has  gotten  into  the  cell,  steps  should 
be  taken  to  remove  it  at  once.  In  case  removal  is  delayed  and  any  considerable 
amount  of  metal  becomes  dissolved  in  the  solution,  this  solution  should  be 
replaced  with  new  immediately,  thoroughly  flushing  the  cell  with  water, 
before  putting  in  the  new  solution.  The  change  should  be  made  when  the 
battery  is  discharged,  and  just  before  charging.  If  in  doubt  as  to  whether  the 
electrolyte  contains  impurities,  a  sample  taken  at  end  of  discharge  should  be 
submitted  for  test. 

17.  Maintaining  the  battery  in  proper  condition. — In  order  that  the  battery 
may  continue  in  the  best  possible  condition,  it  is  essential,  in  addition  to  care- 
fully following  the  points  noted  above,  that  each  individual  cell  in  the  battery 
be  regularly  inspected  with  a  view  to  reducing  to  a  minimum  the  chance  for 
any  of  them  working  irregularly  or  getting  low;  also  that  cell  readings  be 
taken  and  recorded  at  fixed  intervals  in  such  form  that  consecutive  readings 
can  be  easily  compared  and  any  trouble  that  may  have  developed  be  detected 
and  remedied  at  once. 

For  the  individual  cell  inspections  a  portable  lamp  is  required,  so  that  any 
tendency  for  an  accumulation  or  lodgment  of  material  between  the  plates  can 
be  easily  noticed  and  located.  If  the  elements  are  in  glass  jars  an  ordinary 
lamp  with  extension  cord  attachment  will  be  found  most  convenient  and  satis- 
factory, but  if  they  are  in  lead-lined  or  other  opaque  tanks,  then  a  lamp  suitable 
for  immersion  in  the  electrolyte  to  the  bottom  of  the  tank  will  be  necessary. 

When  examining  a  cell,  great  care  should  be  taken  to  look  between  all  the 
plates.  Any  accumulation  of  material  found  between  them  should  be  removed 
at  once.  If  it  is  from  the  plates  themselves,  remove  by  pushing  down  to  the 
bottom  of  the  containing  vessel  with  a  piece  of  hard  rubber  or  wood,  but  if 
foreign  matter  is  present,  it  should  be  withdrawn  from  the  cell.  Metal  of  any 
kind  must  never  be  used  for  the  purpose  in  either  case. 

These  inspections  should  be  so  arranged  that  each  cell  is  examined  at  least 
once  every  month ;  if  it  is  not  convenient  to  go  over  the  entire  battery  all  at 
once,  a  sufficient  number  of  cells  may  be  looked  into,  say  on  one  day  a  week,  to 
get  over  them  all  within  the  month. 

In  addition  to  the  examination  of  the  cells  with  the  lamp,  and  to  noting  near 
the  end  of  each  charge  whether  all  the  cells  are  gassing  equally  well,  readings 
of  the  voltage  and  specific  gravity  of  each  cell  should  be  taken  once  a  week  at 
the  end  of  the  prolonged  charge  and  so  recorded,  preferably  in  a  book  gotten  up 
for  the  purpose,  that  consecutive  readings  can  be  compared. 


STORAGE   BATTERY. 


71 


Rule  a  large  sheet  in  the  following  form : 


Pa*e  1.] 

SI'KCIKIf  liKAVITY. 

[Page  2. 

VOLTAGE. 

Hat.-.    1!HH». 

i  i--2t; 

ia~a 

ISMJ 

12-lii 

I»at.-,  1900. 

11-26 

1-2-2 

!•_'-'.» 

12-16 

(VII   X... 

Rate. 

100 

amperes. 

95 

amperes. 

100 
amperes. 

1 

2 
3 
4 
5 
6 

1201 

1  21  rl 

1199 
1200 

1200 

1199 
1201 
1198 
*1185 
1200 

1200 

1202 
1200 
1201 
1199 



1 
2 
3 
4 
5 
6 

2.51 
2.52 
2.50 
2.52 
2.40 

2.49 

2.51 
2.50 
*2:  27 
2.50 

2.50 
2.52 
2.60 

2.50 
2.49 



60 
61 

59 
60 

til 

1198 
1202 

1200 
1204 

1200 
1201: 

2.50 
2.51 

2.52 
2.52 

2.51 
2.50 

From  the  above  readings  it  will  be  noted  that  on  12-2,  cell  No.  4  is  unusually 
low,  being  15  points  in  specific  gravity  and  0.25  points  in  voltage  lower  than  at 
the  previous  readings,  thus  indicating  something  wrong  with  ihe  cell,  and  on 
examination  it  would  probably  be  found  that  the  cell  was  short-circuited.  After 
a  good  charge  the  cell  again  came  up,  as  is  indicated  by  the  reading  taken  on 
12-9,  no  acid  having  been  added. 

These  readings  should  be  taken  at  the  end  of  charge ;  the  voltage  readings 
always  when  the  current  is  flowing ;  open-circuit  readings  are  of  no  value. 

If  any  of  the  cells  show  readings  lower  than  the  normal  and  do  not  gas  freely 
at  end  of  charge,  then  they  should  be  examined  at  once  with  a  cell  lamp  to  deter- 
mine the  cause  of  the  falling  off. 

18.  Getting  low  cells  into  normal  condition. — A  cell  which  has  been  found  to 
have  gotten  low  will  generally  need  more  than  the  usual  amount  of  charging  to 
get  it  back  into  normal  condition  again,  after  the  cause  of  the  trouble  has  been 
removed.     This  may  be  accomplished  in  several  ways. 

The  first  and  simplest  being  to  overcharge  the  whole  battery,  but  care  should 
be  taken  not  to  carry  this  to  excess. 

The  second,  by  cutting  the  low  cells  out  of  circuit  over  one  or  two  discharges 
and  in  on  the  charges. 

The  third,  by  giving  an  individual  charge  while  the  other  cells  in  the  battery 
are  on  discharge ;  this  may  be  done  from  a  small  dynamo,  usually  motor-driven. 

Before  putting  a  cell  that  has  been  in  trouble  into  regular  service  again,  care 
should  be  taken  that  all  the  signs  of  a  complete  charge  are  present,  viz :  the  rise 
in  potential  and  specific  gravity  to  the  proper  value,  the  gassing  from  the  plates 
and  the  normal  color. 

19.  Sediment. — Another  cause  for  cells  working  irregularly,  especially  after 
they  have  been  in  service  a  considerable  time,  is  the  accumulation  of  sediment 
in  the  bottom  of  the  jar  or  tank,  to  such  a  depth  that  it  touches  the  bottom  of 
the  plates  which  then  become  short-circuited. 

For  this  reason  the  gradually  increasing  amount  of  sediment  should  be  care- 
fully watched  and  removed  before  it  gets  dangerously  near  the  plates.  It  must 
never  be  allowed  to  get  up  to  them. 

As  the  accumulation  is  usually  greatest  under  the  middle  of  the  plates  of  a 
cell,  care  should  be  taken  not  to  be  guided  by  an  examination  under  the  end 
plates  only. 

To  remove  the  sediment,  a  convenient  method,  provided  there  is  sufficient 
free  space  at  one  end  of  the  tank,  is  to  "rake"  it  put  from  under  the  plates  and 
then  ' '  scoop  "  it  up,  always  using  a  device  containing  no  metal  in  its  construction. 

If,  however,  this  method  is  impracticable,  the  electrolyte  should  be  drawn  off 
into  clean  containing  vessels,  the  battery  previously  having  been  fully  charged, 
and  the  cells  then  flushed  with  water  (the  city  supply  may  be  used  for  this  pur- 
pose) in  such  a  way  as  to  thoroughly  stir  up  the  sediment,  the  whole  then  being 
drawn  off,  the  process  to  be  repeated  as  often  as  necessary  to  remove  all  the 
sediment.  If  there  is  not  sufficient  drop  to  allow  of  siphoning,  a  pump  should 
be  used.  Pumps  most  suitable  for  this  purpose  are  of  the  rotary  type,  with 
bronzed  parts. 

After  the  tanks  or  jars  have  been  thoroughly  cleaned,  the  electrolyte  should  be 
quickly  replaced,  to  prevent  undue  heating  and  drying  of  the  negative  plates,  and 
also  the  long  charge  required  by  dry  pla  tes  to  bring  them  to  a  state  of  full  charge. 


72 


HANDBOOK    FOR   ELECTRICIANS. 


In  addition  to  the  electrolyte  withdrawn  from  the  cells,  new  must  be  provided 
to  make  good  that  displaced  by  the  sediment.  This  should  be  of  1.300  or  1.400 
specific  gravity  to  counteract  the  effect  of  the  water  which  was  absorbed  by  the 
plates  during  the  washing,  and  also  to  reduce  the  bulk  of  the  new  supply. 

20.  Keeping  electrolyte  free  from  impurities.  —  Still  another  cause  for  irregu- 
larity in  cells  would  be  the  presence  of  foreign  matter  in  the  electrolyte.     If  it 
is  known  that  any  impurity,  especially  any  of  the  metals  (except  lead)  or  other 
acids,  has  gotten  into  a  cell  in  other  than  very  minute  quantities,  the  electro- 
lyte should  be  replaced  by  new  immediately,  after  the  manner  noted  above  under 
"Electrolyte." 

21.  Battery  used  but  occasionally.  —  If,  for  any  reason,  the  battery  is  discharged 
but  occasionally,  or  the  discharge  is  at  a  very  low  rate,  a  weekly  freshening  charge 
should  be  given. 

22.  Putting  the  battery  out  of  commission.  —  If  the  use  of  the  battery  is  to  be 
discontinued  for  a  time,  say  six  months  or  more,  it  is  very  often  best  to  take  it 
entirely  out  of  service  by  drawing  off  the  electrolyte. 

This  should  be  done  as  follows  : 

After  a  complete  charge,  siphon  off  the  electrolyte  (which  maybe  used  again) 
into  convenient  receptacles,  preferably  carboys  which  have  previously  been 
cleaned  and  have  never  been  used  for  other  kinds  of  acid,  and  as  each  cell  is 
emptied  immediately  refill  with  water.  When  water  is  in  all  the  cells  begin 
discharging  and  continue  until  the  voltage  falls  to 
or  below  1  volt  per  cell  at  normal  load  ;  when  this 
point  is  reached  draw  off  the  water  ;  the  battery  may 
then  stand  without  further  attention  until  it  is  again 
to  be  put  into  service. 

23.  Putting   the   battery  into  commission  again.  — 
To  do  this,  proceed  in  the  same  manner  as  when  the 
battery  was  first  put  into  commission.      After  first 
determining  that  the  polarity  of  the  charging  source 
has  not  been  altered,  so  that  its  positive  pole  will 
still  be  connected  to  the  positive  end  of  the  battery, 
put  in  the  electrolyte  and  start  charging  at  once  at  the 
normal  rate,  continuing  until  the  charge  is  complete  ; 
from  twenty-five  to  thirty  hours  at  this  rate  will  be 
required.     The  completion  of  this  charge  is  determined 

in  the  same  manner  as  are  those  when  the  battery  is  in  94'  Type 
regular  service,  as  noted  above. 

24.  The  attached  form  is  recommended  for  recording  the  readings,  which  should 
be  taken  in  duplicate,  carbon  paper  being  used  to  obtain  the  second  copy  which 
should  be  forwarded  to  the  Company's  office. 


Tank         °e 


(C)  FORMS  FOR  KEEPING  RECORDS  AND   MAKING  TESTS. 

1.  STORAGE  BATTERY  WEEKLY  INSPECTION  REPORT. 

Plant  of Date, ,190     Tinu-j-  r   ,V  \[ 

at 

Consisting  of cells,  type , "Chloride  Accumulator." 


Battery  had  been 


nii 


f°r  ------  h°Ur8  at  avemge  rate  of  ------  ampere*. 


Battery  last  inspected  with  lamp  __________________  (date). 

Cells  (Nos.)  especially  worked  on  during  week  __________________ 

Height  of  electrolyte  above  top  of  plates  ______  inch. 

Water  was  added  to  replace  evaporation  ------------------  (date). 

Temperature  of  electrolyte  ______  °F;  of  air  of  battery  room  ______  °F. 


Cell. 

Volta. 

Specific 
Gravity. 

Cell. 

Volts. 

Specific 
Gravity. 

Cell. 

Volts. 

Specific 

<;ni\ity. 

Remark*. 

1 

31 

61 

2 

32 

62 

3 

33 

88 

4 

34 

M 

5 

65 

6 

36 

06 

7 

37 

•;: 

Bte, 

Etc. 

etc. 

STORAGE   BATTERY. 


73 


2.  TEST  OF  BATTERY  OF  "CHLORIDE  ACCUMULATOR" 

Consisting  of cells,  type Located  at 


u; 

Date. 

Time. 

No.  of 
Cells 
in 
dr. 

Total 
Volts. 

Volts 
per 
Cell. 

Amp. 

Amp. 
llrs. 

PILOT  CELL. 

Remarks. 

Volts. 

Sp.Gr. 

Temp. 

a 

NOTE.  —  Readings  to  be 
taken  half  hourly.    All  of 
the  cells  to  be  in  as  near- 

ly uniform  condition  as 

possible  before  the   test 

is  started. 

_. 

representative  and  in  the 
main  part  of  the  battery. 

a 

3.  TEST  OF  BATTERY  OF  "CHLORIDE  ACCUMULATOR." 

Consisting  of cells,  type Located  at 


CHARGE. 

DISCHARGE. 

CHARGE. 

DISCHARGE. 

Test  taken  bv_ 

TO 

TIME. 

P.M. 

A.M. 

A.M. 

A.M. 

A.M. 

TIME. 

A.M. 

A.M. 

A.M. 

A.M. 

A.M. 

A.M. 

P.M. 

P.M. 

"    P.M. 

"P.M. 

P.M. 

P.M. 

P.M. 

P.M. 

P.M. 

REMARKS. 

Cell. 

Volts. 

Sp.gr. 

Volts. 

Volts. 

Sp.  gr. 

Cell. 

Volts. 

Sp.  gr. 

Volts. 

Volts. 

Sp.  gr. 

1 

36 

The  readings  to  be  taken  at 

2 

37 

the  end  of  charge    and    dis- 

3 
4 

38 
39 

charge;  the  voltage  with  the 
current  flowing,  as  recorded  on 
the    (2)   sheet;    the    specific 

5 

40 

gravity  immediately  after  the 

6 

41 

current  is  off. 

7 

42 

Two  columns  for  "Volts" 

under  "Discharge"  are  pro- 

vided in  case  the  first  set  of 

9 

44 

readings  is  taken   before  the 

10 

45 

battery  is  "  down,"  or  in  case 

11 
12 

46 

47 

"  check  "  readings  are  desired. 
The  time  when  readings  are 

13 

48 

started    and    finished    to    be 

14 

49 

recorded  at  head  of  columns. 

15 

50 

16 

51 

Etc. 

Etc. 

74  HANDBOOK   FOR   ELECTRICIANS. 

(D)  GE:NTSRATOR  A:N"D  CIRCUIT  PA^EI,  A:ND  BATTERY 


Generator  and  circuit  panel  (fig.  95)  and  battery  panel  (fig.  96)  for  use  in 
connection  with  chloride  accumulators  as  designed  and  manufactured  for  the 
U.  S.  Gov't  by  the  Storage  Battery  Company,  Phila.  V.  M.  switch:  1,  bus; 
2,  A  -4-  B  discharge ;  3,  A  charge ;  4,  B  charge ;  5,  +  ground ;  6,  —  ground.  The 
back  connections  will  be  evident. 


o 


© 


© 


© 


THE    SWITCHBOARD. 
(E)  COMBINED  GENEKATOR  AND  BATTERY 


75 


For  use  in  connection  with  chloride  accumulators  where  battery  is  charged 
and  discharged  in  series,  as  designed  and  manufactured  for  the  U.  S.  Gov't  by  the 
E.  S.  Battery  Company,  of  Philadelphia.  Voltmeter  switch:  Point  1,  dynamo- 
point  2,  battery ;  point  3,  +  ground ;  point  4,  —  ground. 


S113D  QN3  WJ3JJ.V8 


76  HANDBOOK   FOR   ELECTRICIANS. 

Fig.  95a  gives  the  S.  B.  connections  when  a  booster  and  end  cells  are  employed 
in  large  installations.  It  is  the  most  economical  disposition  shown. 

(F)  PRECAUTIONS. 

1.  Sulphating,  buckling,  and  disintegrating  of  plates  (positives  are  more  sus- 
ceptible than  negatives)  are  the  three  most  serious  troubles  with  storage  cells  in 
general,  but  they  may  be  avoided ;  if  not  too  far  gone  they  can  be  cured. 

2.  Sulphating  is  a  whitish  scale  that  forms  in  patches  due  to  overcharge ;  to 
standing  too  long  partially  discharged,  or  to  too  strong  electrolyte.     It  is  also 
shown  by  loss  of  capacity  and  a  higher  voltage  than  the  charge  warrants.     If 
slight,  repeated  slow  charge  below  one-half  the  normal  rate  and  discharge  is  the 
remedy ;  if  considerable,  carefully  scrape  off  the  white  scale  prior  to  slow  charge. 
No  attention  need  be  paid  to  a  whitish  loose  precipitate  which  does  not  extend 
into  the  plate,  as  found  by  cutting  into  the  skin  with  the  point  of  a  knife. 

8.  Buckling  or  warping  of  a  plate  from  unequal  action  on  its  two  surfaces  is 
caused  by  excessive  charging  or  discharging  rate  or  sulphating.  To  remedy, 
steadily  press  the  plate  between  two  boards. 

4.  Disintegrating  of  paste  from  plate  results  from  sulphating,  buckling,  or  old 
age  and,  if  well  started,  new  plates  are  the  only  remedy.     It  seldom  or  never 
occurs  in  chloride  plates. 

5.  The  office  of  the  storage  battery  is  to  form  a  reserve  for  feeding  lamps, 
operating  night  signal  sets,  igniting  fuses,  etc.,  in  case  of  accident  to  the 
machinery,  and  to  illuminate  the  magazines  for  short  periods,  so  as  to  avoid 
starting  the  engine. 

6.  A  well-managed  chloride  storage  battery  will  last  indefinitely  on  6  per  cent 
allowance  of  the  cost  for  amortisation  each  year.     Watt  efficiency  should  be 
about  85  per  cent ;  quantity  efficiency,  90  per  cent. 

7.  The  normal  rate  of  charge  and  discharge  is  about  12  amperes  per  square 
foot  of  positive  plate  counting  one  side  only.     The  charge  rate  need  not  be 
exceeded ;  the  discharge  rate,  only  in  emergency. 

8.  Guard  against  disturbing  the  plates  in  jars  while  connecting  or  disconnect- 
ing the  lugs,  and  against  solution  falling  from  the  hydrometer  or  stick,  outside 
of  the  jar. 

9.  Dry  plates  will  keep  indefinitely  in  a  dry  place. 

10.  The  deflection  of  a  voltmeter  across  a  connection  should  be  no  greater  than 
for  an  equal  length  of  lug. 

11.  To  charge  a  portable  battery  of  few  cells  from  a  110-volt  lighting,  a  550- 
volt  trolley  or  an  arc -lighting  circuit  by  placing  in  series  with  the  battery  a  bank 
of  lamps  or  a  rheostat,  is  well  explained  in  figure  98. 

(a)  The  connection  with  an  arc  circuit,  as  in  D,  requires  experience.  The 
switch  is  so  made  that  the  contact  arm  A  when  thrown  to  the  charging  (two 
dotted  lines)  position  shall  not  open  the  light  circuit  nor  short-circuit  the  bat- 
tery A.  Heavy  wire  resistance  R  has  terminal  G  so  spaced  between  B  and  D  that 
the  arm  must  touch  C  before  leaving  B  or  D. 

Or,  R  may  be  permanently  placed  in  the  arc  circuit,  its  E.  M.  F.  verified  before 
switching  in  the  battery  and  after  the  charge  is  finished  and  battery  is  opened, 
R  is  shunted  out  of  circuit.  The  caution  seems  unnecessary  that  while  being 
charged  the  switch  should  be  opened  at  the  first  sign  of  fluctuation  or  stoppage 
of  the  current. 


THE    SWITCHBOARD. 


77 


In  the  case  of  a  battery  of  three  cells  or  6  volts  requiring  a  charging  C  of  5 
amperes  from  an  arc  circuit  of  7  amperes,  R  =  6  -f-  (7  —  5)  =3  ohms. 


IHh 


98.  Charging  Few  Cells. 

^6)  In  the  case  of  the  same  battery  charged  from  a  110- volt  circuit  the  total 
resistance  of  lamps  hot  =  (110  —  6)  -7-5  =  21  ohms. 

(c)  In  all  cases  the  polarity  and  potential  of  the  charging  circuit  must  be 
known  to  be  correct  by  means  of  the  voltmeter  before  closing  it  on  the  battery. 
If  no  voltmeter  is  at  hand,  the  polarity  can  be  ascertained  by  dipping  the  termi- 
nals in  salt  water,  when  the  greater  flow  of  gas  will  appear  at  the  negative 
terminal  which  is  the  one  which  should  be  connected  with  the  negative  of  the 
battery. 


VII.— D.  C.   ELECTRIC  MOTORS. 


(A)   ESSENTIAL  PRINCIPLES  AND  CLASSIFICATION. 

1.  Any  D.  C.  dynaino  supplied  with  current  from  an  external  source  will 
operate  as  a  motor.     The  lead  of  a  motor,  if  any,  is  backward,  not  as  in  a 
dynamo,  forward  or  with  the  rotation. 

2.  To  get  the  direction  of  rotation  of  any  conductor  on  the  motor  arma- 
ture's surface,  hold  the  left  hand  with  its  thumb  and  first  two  fingers  extended 


99.  W=e  Multipolar. 

at  right  angles  to  each  other,  so  that  any  one  of  the  three  lies  parallel  with  the 
conductor  pointing  in  the  direction  of  the  current  through  it,   and  so  that 
another  points  in  the  direction  of  the  lines  of  force  of  the 
field  magnet  ;  then  the  third  will  point  in  the  direction  the 
conductor  is  urged. 

3.  Back  electromotive  force.  —  The  armature  of  a  motor 
revolving  in  a  field,  owing  to  an  external  supply,  has  an 
E.  M.  F.  set  up  in  it  precisely  the  same  as  if  it  were 
revolved  as  a  dynamo.  This  E.  M.  F.  or  (e)  has  (from  the 
rule  with  the  right  hand)  a  direction  opposite  to  that  (E) 
which  actuates  the  motor,  and  is  therefore  called  back  or 
counter  E.  M.  F.  The  motor's  power  varies  directly  with 
the  resultant  E.  M.  F.,  i.  e.,  with  (E—e).  Ex.  If  100  volts 
be  applied  to  the  brushes  of  a  motor  of  2  ohms  internal 
resistance,  and  if  the  armature  be  clamped  to  prevent 
rotation,  the  current  would  be  50  amperes.  But  if  the  100  Motor  Left  Hand. 
armature  is  allowed  to  revolve,  a  counter  (e)  will  be  set  up 

of  say,  96  volts.    The  current  then  through  the  motor  is  -  --  T~h        ~~  =2  amperes 


and  the  power  expended  is  2x100=200  watts. 

4.  Efficiency.  —  The  power  input  (C  amperes  X  E  volts)  is  always  equal  to  the 
useful  output  or  power  at  the  pulley  (torque  in  Ibs-feet  X  revs,  per  sec.) 
plus  the  energy  wasted  per  second  to  overcome  ohmic  resistance,  friction, 

(78) 


ELECTRIC    MOTORS. 


79 


windage,  hysteresis,  Foucanlt  and  eddy  currents.  The  total  wastage  amounts 
to  10  or  15  per  cent.  Efficiency  of  a  motor  =  useful  output  -*-  input  =  80  to  90  per 
cent  usually. 

5.  Modern  D.  C.  motors  are  usually  wound  for  a  constant  potential  supply  of 
500  volts  for  several  miles  transmission,  220  volts  for  a  few  thousand  feet,  and 
110  volts  for  a  few  hundred  feet  as  in 

forts.  Like  modern  generators,  they  us- 
ually have  4  or  more  removable  poles 
projecting  inwardly  from  an  outer  field 
steel  casting  support  toward  an  iron- 
clad armature,  i.  e.,  one  in  which  the 
conductors  are  sunk  and  bound  below 
the  surface  in  slots  parallel  with  the 
axis.  Displacement  of  the  winding  is 
therefore  impossible. 

In  the  construction  both  field  and 
armature  coils  are  formed  on  moulds, 
insulated  and  laid  without  bending  on 
their  cores,  which  are  laminated  trans- 
versely to  their  main  currents.  The 
armature  core  has  air  ventilating  ducts 
parallel  and  perpendicular  to  the  axis 
to  which  it  is  rigidly  held  by  a  spider. 
The  commutator  has  large  diameter  and 
many  bars  insulated  by  mica.  The 
brushes  are  carbon,  radially  placed  with 
little  or  no  lead  and  are  sparkless  from 
full  load  to  no  load  without  adjustment. 

6.  Each    class    has   a    special   use. — 
For  constant  current  supply,  motors  are 

always  series  wound ;  for  constant  potential,  they  are  series,  shunt  or  compound 
wound. 

(a)  The  series  motor  (fig.  101)  has  great  starting  torque  (force  X  lever  arm), 
changes  its  speed  greatly  for  small  changes  of  load,  does  good  work  at  the  dif- 
ferent speeds,  races  dangerously  without  load,  and  is  regulated  by  a  rheostat  in 
series  with  it.  If  its  supply  is  constant  current,  it  may  be  safely  overloaded  to 
the  point  of  stopping;  if  constant  potential,  it  may  run  one-half  hour  on  25  per 
cent  overload.  It  is  suited  to  variable  speed  work  as  in  railroads,  automobiles, 
hoists  and  machines  which  require  increased  torque  when  slowed  down  from 
overload  and  have  an  attendant.  Series  motors  run  parallel  across  constant 
potential  mains,  \vork  well  on  separate  work ;  on  joint  work  each  must  be  geared 
(not  belted)  for  a  speed  corresponding  to  its  share  of  the  voltage. 


lOOa.  W=e  Core  of  M.  P.  Motor. 


101.  Series  Wound. 


(b)  The  shunt  motor  (fig.  102)  has  moderate  torque  at  starting,  gives  nearly 
constant  speed  with  varying  load,  falls  in  speed  only  a  few  per  cent  from  0  to 
full  load,  is  largely  self -regulating,  and  suited  to  blowers,  lifts,  and  lathes.  The 
armature  and  field  circuits  lie  in  parallel  across  the  mains,  and  the  speed  can  be 
regulated  by  a  starting  box  in  either  one  or  in  both ;  the  rheostat  in  the  arma- 
ture circuit  is  essential  at  starting  to  prevent  a  destructive  current.  Several 
shunt  motors  of  like  voltage  may  be  placed  in  parallel,  even  of  unlike  power, 


80 


HANDBOOK    FOR   ELECTRICIANS. 


either  to  work  separately  or  each  to  do  its  part  on  one  shaft ;  or  in  series,  to  work 
separately. 

(c)  A  compound  motor  (fig.  103)  is  cumulatively  or  differentially  wound — a 
compound  dynamo  as  a  motor  has  the  latter  winding.  The  f  onner  kind  is  com- 
ing into  use.  It  has  increased  torque  at  slower  speed,  is  partly  self -regulating, 


102.  Shunt  Wound. 

and  is  adapted  to  work  where  heavy  overloads  occur  and  close  regulation  is  not 
important,  such  as  for  printing  presses  and  hoists.  Their  supply  is  constant 
voltage  only. 


(B)  REGULATING  A!ND  PROTECTING  APPARATUS. 

1.  When  a  motor  armature  is  at  rest  there  is  no  counter  E.  M.  F.,  and  if  the 
potential  of  the  supply  were  closed  upon  it,  the  current  would  be  destructive. 
Hence,  a  starting  and  stopping  rheostat  (fig.  103)  is  always  put  in  series  with  the 
motor  and  its  resistance  is  gradually  cut  out  as  the 

motor  gains  speed  and  counter  E.  M.  F. 

When  a  starting  box  has  not  wire  of  sufficient 
cross-section  to  carry  the  motor  current  for  any 
length  of  time  without  overheating,  the  switch  must 
not  remain  on  a  point  longer  than  two  or  three  sec- 
onds. When  the  rheostat  wire  is  large  enough  to 
carry  the  current  indefinitely,  the  box  is  a  speed 
regulator  or  controller. 

2.  The  motor  is  slowed  down  and  finally  stopped 
by  turning  the  same  contact  arm  to  throw  resistance 
into  the  motor  circuit  and  thus  gradually  to  dimin- 
ish the  current  from  full  strength  to  zero.     To  open 
the  circuit  as  at  the  main  switch  while  full  current 
is  flowing  would  endanger  the  insulation  from  the 
induced  extra  current. 

3.  In  addition,  a  motor  requires  to  be  protected 
against  sudden  excess  of  current  by  an  overload 
automatic  circuit  breaker  in  one  or  both  of  its  feed- 
ers, which  is  quicker  and  more  certain  than  a  fuse ; 
also  by  an  underload  automatic  circuit  breaker  against 
the  fall  of  the  current  or  of  the  potential  below  a 
certain  limit  due  to  a  cross  or  other  accident  which 
is  liable  to  be  followed  by  a  rush  of  full  current  that 

would  destroy  the  motor  at  rest.  103.  Compound  Motor. 


ELECTRIC   MOTORS. 


81 


(a)  Diagram  of  General  Electric  S.  and  S.  rheostat  (fig.  104)  with  automatic 
release  (underload  C.  B.)  in  armature  circuit  of  small  series  motor.  Box  is 
shown  for  small  shunt  motor. 


Release  magnet 


-      t  °        T 

iFV-om  supplyVS1 
circuit. 


Cut-out 


00000000 
Field 


104.  Diagram  of  S.  and  S.  Rheostat. 

(b)  Diagram  of  General  Electric  S.  and  S.  rheostat  (fig.  105)  for  larger  series 
motor  with  underload  release  magnet  in  the  armature  circuit  and  magnetic 
blow-out  at  the  first  step ;  stops  on  left-hand  side  are  connected  with  middle 
pivots  of  coils  on  right-hand  side. 


00000000 

105.  Diagram  of  S.  and  S.  Rheostat  for  Larger  Series  Motor. 

(c)  The  armature  of  the  retaining  magnet  is  adjusted  by  means  of  the  screw 
and  nut  to  hold  at  a  current  equal  to  about  55  per  cent  of  the  full-load  amperes 
of  the  smallest  size  of  motor  with  which  the  rheostat  is  used.  Therefore  these 
series  motors  must  be  loaded  to  about  one-half  their  capacity,  or  the  armature 
will  not  be  held  by  the  magnet. 

Boxes  for  S.  and  S.  rheostats  (fig.  106)  for  shunt  motors,  two  larger  showing 
magnetic  blow-out. 

1714—6 


82 


HANDBOOK   FOR    ELECTRICIANS. 


(d)  Starting  and  stopping  rheostat  (figs.  107-8)  for  shunt  motor  with  no 
voltage  (underload),  automatic  circuit  breaker  in  the  field  circuit,  with  overload 
release  and  magnetic  blow-out  in  the  main,  and  with  switch  shown  in  the  ' '  On  " 
position  in  fig.  108.  Mid-points  of  resistance  coils  are  connected. 


107.  Starting  and  Stopping  Rheostat  for  Shunt  Motor  with  no  Voltage. 


/T^^na^u^• 


108.  Wiring  of  Starting  and  Stopping  Rheostat. 


Vom  Supply. 
Circuit 


Cut-out, 


Switch 


De-tails  of  Release  TTla^net 


109.  Rheostat  and  Connections. 


ELECTRIC    MOTORS. 


83 


The  switch  is  moved  gradually  clockwise  against  the  action  of  the  spring  and 
held  by  the  U.  L.  upper  magnet.  If  the  potential  of  supply  falls  off  say  25  per 
cent,  the  magnet  releases  the  armature  on  the  switch  which  flies  to  the  "  Off  " 
position  where  the  arc,  if  any,  is  blown-put. 

If  the  current  exceeds  the  allowable  limit  in  the  O.  L.  or  lower  magnet  of 
heavier  wire,  the  armature,  lifted  against  the  two  pins,  short-circuits  the 
underload  magnet  which  then  operates  as  above.  The  spindle  of  the  switch  or 
contact-arm  is  connected  by 
wires  with  one  side  of  both  mag- 
nets and  the  left  pin. 

(e)  Figs.  109  and  110  show 
rheostat  and  connections  for 
large  shunt  motor,  with  under- 
load, circuit  breaker  of  differ- 
ent form,  whose  details  are 
plainly  indicated  in  separate 
cuts. 

(/)  Automatic  O.  L.  and 
U.  L.  circuit  breaker  (fig.  Ill) 
is  held  in  the  "On"  position 
against  the  tension  of  a  spiral 
spring  in  the  hub. 

6.  Directions  for  installing 
rheostats  are  as  follows : 

(a)  If  the  rheostat  must  be 
attached  to  ironwork  of  any 
kind,  special  care  should  be 
taken  to  thoroughly  insulate  it 
from  the  iron. 

Attach  the  small  rheostats 
which  have  no  magnetic  blow- 
out, to  the  wall  with  the  retain- 
ing magnet  on  the  right-hand 
side  and  the  connection  ter- 
minals at  the  bottom.  The 
large  rheostats,  with  magnetic 
blow-out,  should  be  installed 
with  the  magnets  at  the  top, 


111.  Automatic  O.  L.  and  U.  L.  Circuit  Breaker. 


otherwise  the  arc  at  the  blow-out  may  cause  trouble. 

(b)  Adjusting. — The  rheostats  are  adjusted  so  that  the  arm  will  return  to  the 
"Off  "  position  from  any  step.     If  it  does  not,  the  steps  are  generally  found  to  be 
dirty.     If  on  cleaning  them,  the  arm  still  works  too  stiffly,  slack  up  the  adjusting 
nuts  that  are  on  top  of  the  arm.     These  nuts  must  be  left  securely  locked  or  the 
arm  will  again  get  out  of  adjustment. 

The  armature  of  the  retaining  magnet  is  adjusted  by  means  of  the  screw  and 
nut  to  hold  at  the  average  field  current  of  the  smallest  size  of  motor  with  which 
the  rheostat  is  used. 

Sometimes,  however,  the  field  current  may  be  less  than  the  average,  and  it  is 
therefore  not  enough  to  hold  the  armature  to  the  magnet.  In  this  case  the 
point  of  the  screw  should  be  turned  back  into  the  armature  until  the  latter  holds 
securely.  The  adjustment  also  provides  for  the  releasing  of  the  armature  when 
the  field  current  falls  to  at  least  one-quarter  of  the  average,  and  if  any  change  is 
made  in  the  adjustment  to  have  the  armature  hold  more  securely,  a  trial  should 
be  made  starting  the  motor,  then  cutting  off  the  supply  of  current  to  see  that 
the  release  takes  place  at  about  the  time  that  the  motor  has  slowed  down  to  one- 
quarter  speed.  If  the  armature  does  not  release  by  that  time  there  is  danger 
that  it  will  not  do  so  in  time  to  protect  the  motor. 

If  the  armature  can  not  be  made  to  hold  securely  with  the  range  of  adjust- 
ment, get  a  new  magnet  spool  to  suit  the  conditions.  The  overload  release  is 
adjusted  by  means  of  the  screw  below  the  armature,  to  operate  when  the  amperes 
increase  to  the  amount  on  the  plate  screw  along  the  upper  edge — usually  100, 
125,  or  150  per  cent  of  the  full  load  current  of  the  largest  motor  for  which  the 
rheostat  was  built. 

(c)  The  connections  are  such  that  the  field  of  the  motor  is  made  as  soon  as  the 
main  supply  switch  is  closed.     Do  not  test  the  line  for  current  by  touching  the 
first  step  with  the  arm  and  then  allowing  it  to  go  back  to  the  "Off"  position; 
this  draws  an  unnecessarily  long  arc  at  the  first  step,  which  uselessly  burns  the 
arm  and  contact. 


84 


HANDBOOK    FOR    ELECTRICIANS. 


(d)  Renewals.— It  the  first  step  which  is  of  copper  and  hexagonal  in  shape 
becomes  burned,  it  may  be  removed  by  unscrewing  it  and  substituting  another. 
The  arm  may  also  be  easily  taken  off  and  smoothed  or  renewed. 

(C)  OPERATION  AXD  CARE  OF  MOTORS. 

STARTING. 

I.  See  that  all  nuts  and  parts  are  tight,  that  connections  are  correct,  that 
the  commutator  is  clean,  that  the  brushes  are  properly  set,  and  that  the 
starting  switch  is  in  the  "Off"  position.  Turn,  if  possible,  the  armature  by 
hand,  to  see  if  it  is  free.  Close  the  main  switch.  Turn  the  rheostat  switch 
steadily  clockwise  until  it  strikes  the  automatic  release,  so  that  the  motor  starts 
slowly  and  increases  uniformly  to  full  speed,  taking  about  one-half  minute  to 
turn  the  switch.  If  the  motor  is  new,  run  it  empty  for  a  time  and  see  that  all 
parts  operate  properly  when  the  motor  is  partially  and  fully  loaded. 

If  a  motor  fails  to  start  after  beginning  to  cut  out  the  resistance,  turn  the 
switch  off  to  prevent  accident  before  beginning  to  explore.  With  a  voltmeter, 
or  with  the  hands  on  low  potentials,  ascertain  if  the  supply  is  present.  If  it  is, 
take  off  the  load,  close  the  main  switch,  and  see  if  the  armature  moves.  If  it 
does  not,  proceed  from  the  mains  with  a  voltmeter  in  search  of  a  broken  circuit. 
The  break  may  be  in  the  rheostat. 


112.  W-e  S.  and  S.  Box. 

If  motor  terminals  show  potential  and  poles  have  no  magnetism,  there  is  a 
break  in  the  field  of  a  shunt  or  compound  motor,  or  between  the  terminals  of  a 
series.  But  if  the  poles  are  magnetized,  see  if  brushes  are  at  the  neutral  point 
and  pressed  down,  if  commutator  is  clean,  if  adjacent  poles  are  not  alike,  or  if 
coils  have  not  a  short  circuit. 

RUNNING. 

2.  (a)  See  that  the  oil  rings  or  feeds  distribute  oil  properly,  that  the  belt 
runs  in  the  middle  of  the  pulley  without  tendency  to  thrust  the  armature 
toward  one  end,  and  that  no  part  gets  overheated.  The  heating  of  any  part 
is  probably  normal  if  its  temperature  is  110°  F.  or  less  above  that  of  the  sur- 
rounding air  after  several  hours'  continuous  run  on  full  load,  as  tested  by  a 
thermometer  placed  upon  it  and  surrounded  by  waste.  The  danger  point  has 
not  been  reached  if  the  hand  can  bear  long  contact  without  discomfort.  Hot 
coils  are  usually  due  to  overload,  short  or  partly  open  circuit.  •  Commutator  and 
brushes  often  get  hot  from  sparking  or  friction. 

(5)  From  time  to  time,  or  whenever  the  bearings  show  signs  of  heating,  draw 
off  the  oil  and  replace  with  new  by  bringing  up  the  level  until  the  rings  flush  the 
shaft  freely,  care  being  taken  not  to  overflow  the  bearings. 

A  hot  box  is  due  to  poor  oil,  grit,  rough -bearing  surface,  tight  box  or  belt, 
shaft  bent  or  out  of  line,  or  overload. 


ELECTRIC   MOTORS. 


85 


(c)  The  usual  load  causes  a  certain  rise  of  temperature  in  each  part  which  is 
well  known  to  the  watchful  attendant,  and  any  increase  of  that  amount  requires 
immediate  correction  without,  if  possible,   stopping  the  machine.     If  smoke 
appears,  damage  has  been  done. 

(d)  Irregularity  of  speed  may  be  expected  in  a  series  motor  whose  load  varies. 
But  a  shunt  motor  changes  speed  slightly  for  large  variation  of  load ;  if  over- 
loaded it  heats.     Abnormally  low  speed  indicates  overload,  .short  circuit  or  a 
defective  contact. 

(e)  Keep  all  parts  of  the  motor  free  from  dirt,  damp,  waste  oil  and  carbon  dust. 

STOPPING. 

3.  Turn  steadily  the  rheostat  switch  contraclockwise  to  the  open  stop ;  then 
open  the  main  switch.     The  order  is  the  reverse  of  that  in  starting.     Finally, 
take  the  same  precautions  as  in  leaving  dynamos. 

4.  ' '  Faults  "  in  motors,  together  with  their  causes  and  remedies,  are  for  the  most 
part,  the  same  as  for  dynamos  (page  52).     The  motor  on  account  of  its  duty  is 
not,  as  a  rule,  so  accessible  as  a  generator ;  its  care,  equally  important,  is  more 
likely  to  be  neglected. 

Prevention,  not  cure,  is  the  rule  for  motor  or  dynamo  troubles. 

Dirt,  sparking  or  overheating  usually  affords  conclusive  testimony  regarding 
the  attendant's  fitness. 

Oil  cans,  tools,  or  loose  iron  near  the  motor  in  operation  are  liable  to  be  drawn 
into  the  armature. 

To  reverse  a  D.  C.  motor,  reverse  the  current  through  the  armature  (usually) 
or  the  field — not  both. 

The  voltage  of  supply  should  be  within  5  per  cent  of  that  for  which  the  motor 
was  built. 

Excess  voltage  to  shunt  motors  will  heat  the  fields  and  somewhat  increase  the 
speed ;  scant  voltage  will  heat  the  armature  and  lessen  the  speed. 

Remember  main  switch  first,  rheostat  last  in  starting;  rheostat  first,  main 
switch  last  in  stopping. 

Do  not  keep  the  rheostat  switch  long  on  one  stop,  except  the  end  ones,  unless 
the  rheostat  was  built  to  carry  the  full  current  indefinitely  as  a  regulator  or 
controller. 

Oil  reservoirs  may  be  half  drawn  every  three  or  four  weeks  and  refilled  with  new. 

High-grade,  dense,  mineral  oil,  free  from  grit,  is  the  proper  lubricant ;  after 
filtration  it  may  be  reused. 

Keep  posted  all  motor  circuits  and  manufacturer's  directions. 

A  series  motor  always  runs  reverse  to  its  direction  as  a  generator ;  a  shunt,  in 
the  same  direction ;  a  differential  compound,  according  to  the  stronger  field. 

(D)  SPECIAL  FORMS  OF  MOTORS  IN  SERVICE. 

1.  (a)  The  Leonard  motor  control  for  guns,  turrets,  passenger  elevators,  etc., 
avoids  violent  stresses,  bad  sparking,  and  affords  complete  control  with  precision 


(b)  In  fig.  113,  M  is  the 
motor  whose  field    is  con- 
stantly excited  direct  from 
the  mains.     G  is  the  genera- 
tor, likewise    excited,   but 
through  the  reversing  field 
rheostat  C.     The  brushes  of 
M  and  G  are  permanently 
connected. 

(c)  To  start  the  motor  the 
generator's  field  is  weakly 
excited.      As   resistance  is 
cut    out    of  C,   G  delivers 
stronger  current  to  M  and 
increases   the    speed.     The 
rheostat     contact     arm    is 
divided  by  insulation  at  the 
pivot.     Turning  it  to    left 

reverses  the  G  field  and  M's  113-  system  for  Training  Guns. 

motion. 

2.  The  recording  watt-hour  meter  (fig.  114)  in  general  use  is  a  compound 
wound  ironless  motor,  whose  main  field  coil  carries  the  main  service  current, 
and  whose  armature  of  fine  wire  lies  with  dead  resistance  across  the  mains. 


86 


HANDBOOK    FOR   ELECTRICIANS. 


The  revolutions  varying  as  the  C  and  E  of  supply  and  therefore  as  their  pro- 
duct, are  recorded  as  units,  tens,  etc. ,  on  the  dials.  The  shunt  field  is  added  to 
compensate  for  friction.  A  copper  disc  on  the  armature  shaft  revolves  between 
the  poles  of  an  adjustable  magnet,  which  can  slow  down  the  motion  16  per  cent 
or  less  as  desired. 


114.  Measures  Electrical  Energy. 

3.  Dynamotors,  motor  generators,  and  boosters  are  rotating  transformers  of 
direct  current  having  a  dynamo  and  a  motor  armature  winding  and  two  com- 
mutators usually  on  the  same  shaft. 

(a)  The  dynamotpr  has  two  armatures,  or  two  separate  windings  on  one 
armature  revolving  in  one  magnetic  field.  Its  place  in  the  Teazer  system  for 


115.  Thompson's  Recording  Watt  Meter. 


116.  One  of  the  Special  Motors. 


starting  a  main  motor  without  taking  excessive  starting  current  from  the 
mains  is  shown  by  "Teazer  Armature  "  in  fig.  116. 

The  left  commutator  belongs  to  the  motor  winding  on  the  armature ;  the 
right  commutator,  to  the  dynamo  winding  which  has  about  one-fifth  of  the 
potential  of  the  motor's  winding.  At  starting,  the  Teazer  dynamo  supplies 
about  one-fifth  of  the  main  voltage  to  the  main  motor,  giving  proper  torque  at 
low  speed  without  draining  more  than  about  one-fifth  of  the  current  from  the 
supply  mains  which  would  be  taken  without  the  dynamotor.  When  the  main 
motor  has  reached  the  highest  speed  attainable  in  this  way,  it  can  be  switched 
to  the  supply  mains  and  the  Teazer  circuit  switched  out  without  excessive  drain 
from  the  mains. 


ELECTRIC   MOTORS. 


8? 


(b)  The  motor  generator  (fig.  117)  has  two  armatures  revolving  on  one  shaft 
in  separate  fields.  The  motor  commutation  is  at  one  end,  the  dynamo's  at  the 
other.  It  is  not  so  efficient  a  transformer  as  the  dynamotor.  but  its  dynamo 
voltage  may  be  given  greater  range  and  its  modes  of  construction  and  operation 
are  simpler  in  charging  batteries,  electroplating,  supplying  telegraph  trunk  lines 
or  current  to  laboratories. 


117.  Motor  Generator. 

(c)  A  booster  is  an  electrically  or  mechanically  driven  transformer  whose 
dynamo  commutator  is  in  the  main  circuit  at  a  distant  point  to  raise  the  voltage 
there.  Both  the  main  and  generated  currents  flow  together  in  the  dynamo 
armature  winding,  which  has,  therefore,  very  thick  copper.  Boosters  are 
placed,  for  instance,  at  the  ends  of  long  feeders  running  from  the  same  bus  bars 
as  short  feeders,  to  keep  the  potential  the  same. 


VIII.— ELECTRIC  HOIST  WITH  AUTOMATIC  SAFETY  STOP. 


It  is  applied  to  two  platforms,  G  G,  either  of  which  is  drawn  upward,  while 
the  other  descends,  by  a  winch  driven  by  a  motor  through  worm  or  train  gear. 
A  5-horsepower  motor  can  raise  2,000  pounds  counterweigh  ted  by  600  pounds  of 
the  other  platform  at  the  rate  of  1  foot  per  second.  The  design  is  simple,  inex- 
pensive, and  the  motor  and  hoist  are  fairly  well  protected. 

1.  JJ/isthe  motor  with  both  series  and  shunt  fields,  the  latter  being  excited 
when  M  S  is  closed.     R  S  is  a  three-pole  reversing  switch  shown  in  position  for 
the  right-hand  platform  to  ascend. 

2.  The  controller  has  a  starting  rheostat,  R  It ;  a  hand  lever,  W;  a  spring  lever, 
V;  an  underload  release,  U  L ;  and  an  overload  release,  O  L.     The  magnet  U  L 
depends  for  its  excitation  upon  the  voltage  of  the  motor  terminals  and  also  upon 
the  integrity  of  its  circuit  at  any  one  of  the  four  points  —  O  L,  R  S,  E,  or  F.    The 
main  circuit  from  M  S  is  through  the  electro-magnetic  brake  E  B,  series  fields 
OL,  to  the  contact  piece  b;  when  the  lever  V  is  held  down  by  U  L  magnet,  the 
circuit  is  closed  from  b  through  d,  V,  W,  R  h  (or  direct  after  the  motor  has 
attained  full  speed),  to  RS,  MtoMS. 

3.  The  main  circuit  is  broken  either  when  the  lever  V  is  released  (e  and  /  taking 
the  spark) ,  or  when  Wis  moved  to  the  left  (k  and  I  taking  the  spark) .     The  lever 
V,  when  released  by  U  L,  is  carried  to  the  right  by  the  spring  at  its  axis  until  it 
strikes  W.     The  rheostat  may  be  designed  for  running  the  motor  continuously 
at  different  speeds,  or  as  a  starting  box  not  to  be  in  the  circuit  longer  than 
thirty  seconds! 

4.  S  is  a  baby  switch  held  open  by  a  spring.     Its  object  is  to  close,  if  desired, 
the  U  L  magnet  circuit  when  open  at  E  or  F. 

5.  A  and  A  are  the  devices  for  automatically  breaking  the  circuit  through  UL, 
and  thus  the  main  circuit  when  the  platform  ascending  strikes  the  lug  g,  which 
is  adjustable  on  the  bar  sliding  in  guides  h.     On  the  lower  end  of  this  bar  an 
insulate  copper  wedge  makes,  when  down,  contact  between  two  copper  terminals 
at  E  or  F,  and  breaks  it  when  up,  thus  making  or  breaking  the  circuit  through 
U  L.    E  and  F  are  alike  and  adjustable  vertically  6  inches. 

6.  The  right-hand  platform  is  at  its  upper  level,  the  left-hand  is  at  its  lower ; 
the  circuit  through  armature  M  has  been  broken  and  Fis  up  against  W.    If  now 
we  try  to  start  the  motor  without  reversing  R  S,  the  circuit  through  If  will  still 
be  open  at  E.    But  throw  R  S  down  and  the  circuit  through  U  L  will  be  closed 
at  F,  and  the  left-hand  platform  can  be  raised. 

7.  To  start  the  motor  at  all,  W  must  always  be  brought  up  to  the  left,  pushing 
V  before  it  until  held  by  the  underload  magnet  U  L ;  then  W  may  be  moved  to 
the  right,  closing  the  circuit  first  through  R  h  and  at  last  without  it. 

8.  When  the  left-hand  platform,  on  nearly  reaching  its  upper  level,  engages  g 
and  opens  F,  the  main  circuit  will  be  opened  at  b  and  the  motor  will  stop. 

9.  If  it  is  necessary  to  move  the  platform  farther  up  after  the  circuit  has  been 
broken  at  E  or  F,  the  switch  S  may  be  closed  and  the  platform  may  then  be 
moved  by  the  motor.     So  long  as  S  is  closed  V  will  not  be  released  except  for  no 
voltage  or  overload. 

10.  The  motor  may  be  slowed  down  or  even  stopped  by  moving  W  to  the  left, 
provided  R  h  is  large  enough  to  carry  the  current. 

11.  The  electro-magnetic  brake  on  the  gear  wheel  next  the  motor  armature 
automatically  clamps  it  whenever  the  main  current  ceases  and  the  motor  stops. 
It  gives  a  quick  stop  for  heavy  or  light  loads. 

12.  If  the  electric  machinery  is  disabled  the  motor  is  quickly  thrown  out  and 
the  platform  can  still  be  raised  by  a  crank  handle  and  gearing. 

(88) 


ELECTRIC    HOIST. 


89 


IX.— SEARCH-LIGHT  PROJECTORS. 


THE  GO-INCH  DIAMETER  SCHUKERT  SEARCH  LIGHT 
AT  FORT  MONROE  (Fig.  12O). 

With  150  amperes,  at  about  60  volts,  it  has  194,000,000-candlepower.  On  a 
clear,  dark  night  a  person  within  its  beam,  12  miles  distant,  can  read  ordinary 
print ;  it  lights  up  an  object  2£  miles  distant  with  the  brightness  of  the  full  moon, 
and  it  will  enable  a  person  near  the  projector  to  distinguish,  with  the  aid  of  a 
glass,  a  vessel  at  6  miles  distance. 

(A)  THE  U.  S.  GOVERNMENT  PROJECTORS 

Are  supplied  by  the  General  Electric  Company  in  the  following  sizes  or 
diameter  of  reflector : 


CONTROL. 

<'I  -1MJEXT. 

CARBONS. 

(Hand,  H;  pilot 
house,   P;  elec- 
tric, E.) 

SIZE. 

Ampere*. 

Volte  at  Arc. 

Positive— 
Cored. 

Negative. 

H.  or  P. 

18" 

35 

47-50 

H''x>'  .." 

•V  x  .'."solid. 

H.,  P.  or  K. 

24" 

50 

L&-4S 

1     "  x  122" 

%"  X  ~"  c,,ivd. 

H.  or  E. 

30" 

80 

49-53 

l%"  x  12  " 

7S"  x  7"  cored. 

H.  or  E. 

36" 

130 

60-68 

i%"  x  12  " 

l"  x  7*  cored. 

All  are  fitted  with  true  parabolic  ground  glass,  silver-plated  mirrors,  as  speci- 
fied for  standard  use  in  the  Navy  Department.  The  light  reflected  from  the 
parabolic  mirror  is  whiter  and  more  penetrating  than  from  a  spherical  mirror. 


I 


121.  Rheostat  for  U.  S.  Government  Projector. 

(00) 


120.  6()=inch  Diameter  Schukert  Search  Light  at  Fort  Monroe. 


BQ 


SEARCH-LIGHT   PROJECTORS. 


91 


All  projectors  are  fitted  with  horizontal  automatic  ratchet-feed  focusing  lamps. 

The  lamps  are  designed  to  throw  the  greatest  possible  amount  of  light  on  the 
reflector,  and  screen  shutters  are  provided  to  prevent  the  direct  rays  from  leaving 
the  projector,  so  that  all  the  rays  of  light  are  reflected  and  sent  out  parallel. 

Both  positive  and  negative  carbons  are  fed  automatically  at  the  same  time, 
and  are  so  proportioned  that  the  arc  remains  in  the  focus  of  the  mirror  until 
they  are  entirely  consumed. 

The  carbon  holders  or  carriages  are  designed  for  vertical  and  horizontal  adjust- 
ment of  the  carbons,  and  by  means  of  a  magnet  fastened  on  the  inside  of  the 
projector  and  surrounding  the  arc  on  all  sides  but  the  top,  the  arc  is  made  to 
burn  steadily  near  the  center  of  the  carbons  and  in  focus  with  the  mirror. 

In  order  to  obtain  the  best  results  the  carbons  must  be  hard,  homogeneous, 
and  of  the  best  quality.  Soft  carbons  fuse  and  make  ' '  mushrooms"  which  cut 
out  a  large  portion  of  the  light  and  prevent  the  arc  from  burning  steadily. 

All  projectors  are  designed  to  operate  on  direct  current  incandescent  circuits. 
A  regulating  resistance  of  G.  S.  ribbon  (fig.  121)  is  placed  in  series  with  the  lamp 
to  reduce  the  voltage,  80  or  110,  to  the  proper  potential,  which  varies  from  40  to 
60  volts,  according  to  the  size  of  the  lamp  and  current  consumed. 

(B)  METHODS  OF  CONTROL.. 

1.  The  beam  of  light  from  the    hand    control    projectors  can  be  trained 
vertically  or  horizontally  by  the  operator  standing  at  the  projector  and  moving 
the  barrel  in  the  desired*  direction  with  the  handles.     A  star  wheel,  mounted  on 
the  arm,  clamps  the  quadrant  part  of  the 

trunnion  and  acts  as  a  locking  device  by 
means  of  which  the  barrel  of  the  projector 
may  be  held  at  any  desired  angle. 

2.  The  pilot-house  control  projectors,  en- 
tirely of  brass  (fig.  122),  are  mounted  on  top 
of  the  pilot  or  other  house  and  operated  from 
within.  Both  horizontal  and  vertical  move- 
ments of  the  beam  of  light  are  accomplished 
by  means  of  the  same  lever  which  is  located 
conveniently  within  reach  of  the  pilot.    The 
projector  may  be  locked  at  any  desired  angle 
by  turning  the  handle  of  the  lever  so  that  it 
screws  against  the  quadrant  like  a  set  screw. 
It  has  conductor  rings  and  brushes  in  the 
base  so  that  the  projector  can  be  rotated  in 
a  horizontal  plane.     If  the  projector  is  to  be 
located  at  some  distance,  the  above  mech- 
anism is  adapted  to  rope  belting. 

3.  Electrically  controlled  projectors  (fig. 
123)  may  be  operated  from  a  distance.  They 
have  two  electric  shunt  motors  mounted  in 
the  base  of  the  projector,  one  motor  operat- 
ing a  train  of  gears  controlling  the  vertical 
movement,  and  the  other  motor  operating 
another  train  of  gears  controlling  the  hori- 
zontal movement  of  the  projectors.     These 
motors  are  regulated  by  a  controller  con- 
veniently located  and  connected  to  the  pro- 
jector by  seven  conductors.     The  movement 
of    the    beam  of  light  corresponds  to  the 
movement  of  the  handle  of  the  controller, 
and  both  horizontal  and  vertical  movement 
can    be  obtained    at    the    same    time.     On 
releasing  the  handle  of  the  controller,  it  is 
brought  back   by  a  strong    spring    to  the 
neutral  position,  short-circuiting  the  arma- 
tures of  the  motors  and  holding  the  projector  locked  in  position.     An  electrically 
controlled  projector  can  also  be  operated  as  a  hand  control  projector,  by  open- 
ing the  circuit  switch  on  top  of  the  controller  and  releasing  the  clutches  con- 
nected to  the  motors  in  the  base  of  the  projector. 

The  drum  rotates  on  its  trunnions  and  can  be  elevated  70°  above  and  lowered 
30°  below  the  horizontal  position.  The  turntable  can  be  revolved  freely  in 
either  direction  in  a  horizontal  plane. 


122.  Pilothouse  Control. 


92  HANDBOOK   FOR   ELECTRICIANS. 

With  electrical  control,  the  highest  speed  obtainable  in  the  horizontal  plane 
is  a  movement  of  360°  in  thirty  seconds,  and  in  a  vertical  plane  100°  in  sixty 
seconds.  The  motors  may  be  operated  at  four  slower  speeds  and  also  by  steps, 
the  angle  of  each  step  being  less  than  a  degree,  that  is  to  say,  about  one  third 
of  the  area  covered  by  the  beam. 

4.  In  general  the  projector  is  designed  to  take  either  a  spherical  or  a  parabolic 
mirror.  The  trunnions  being  mounted  on  slides,  allow  the  drum  to  be  balanced 
with  either  mirror.  The  mirror  is  so  mounted  in  a  brass  frame  that  it  is  securely 
protected  against  concussion  and  provision  is  made  for  expansion  due  to  heat. 

The  plain  front  door,  used  when  long  range  and  small  area  of  beam  are 
required,  is  composed  of  strips  of  plate  glass. 

When  projectors  are  required  to  furnish  a  beam  of  light  covering  a  wide  area, 
at  shorter  range,  the  front  door  is  made  up  of  strips  of  glass  ground  plano-convex, 
each  strip  being  a  lens,  with  the  convex  side  outward.  The  beam  of  light  pass- 
ing through  this  door  is  diverged,  making  it  wider  but  not  increasing  its  height. 
These  diverging  doors  are  for  either  10C,  20°,  or  40°  divergence  for  any  projector. 

(C)  NUMBER  AND  NAMES  OF  PARTS. 

1.  The  hand-control  U.  S.  projector  is  complete  with  the  following  parts: 
The  base  with  all  the  gears ;  turntable  with  arms  and  drum ;  1  mirror ;  1  front 
door  with  plain  glass ;  1  front  door  with  diverging  glass ;  1  box  for  front  doors ; 
1  lamp;  1  rheostat;  1  canvas  cover;  125  positive  carbons  in  tin  boxes;  125  nega- 
tive carbons  in  tin  boxes ;  1  extra  set  of  plain  glass  front  door  strips  in  plain 
wooden  box.     One  tool  box  containing  the  following  articles :  1  crank-handled 
socket  wrench  for  lamp  feed ;  1  wTooden -handled  socket  wrench  for  adjusting 
carbons ;  1  smoked  glass  with  frame ;  1  dust  brush ;  1  small  dusting  brush  for 
lamp;  1  chamois  skin  for  polishing  mirror;  1  spare  spring  for  starting  magnet; 
1  spare  spring  for  feeding  magnet ;  1  contact  spring ;  1  contact  screw ;  2  round 
smoked  glasses ;  1  round  ground  glass ;  2  pairs  of  carbon  holder  clamps,  screws, 
and  washers;  43  extra  lava  insulators;  1  small  wrench  for  8-32  and  10-32  nuts. 

2.  The  pilot-house  controlled  projector  has  the  same  apparatus,  except  pedes- 
tal, but  in  addition  rope  and  guide  pulleys. 

3.  The  electrically-controlled  projector  is  furnished  complete  with  the  same 
parts  as  the  hand-controlled  projector,  together  with  the  following  additional 
parts :  1  controller  stand  and  canvas  cover ;  1  controller  cable  25  feet  long,  with 
connecting  plugs  at  each  end ;  1  controller  receptacle ;  2  pairs  of  carbon  brushes 
for  motors ;  2  20-arnpere  fuses  for  controller ;  6  8-32  nuts. 

(D)  INST AIDING  PROJECTORS. 

The  arrowhead,  which  is  cast  or  painted  on  the  base  or  the  pedestal  of  the 
projector,  should  point  aft.  Otherwise,  the  maximum  allowable  motion  of  the 
projector  can  not  be  obtained  on  account  of  the  stop  pin  which  is  inserted  to 
prevent  twisting  the  cables. 

The  current  should  be  led  directly  from  the  switch  board  in  the  dynamo  room 
to  a  switch  which  should  be  mounted  near  the  projector.  A  rheostat  should  be 
placed  in  series  in  the  circuit,  and  also  an  ammeter  to  indicate  the  current. 

1.  Hand  control  projectors  are  shipped  assembled,  so  that  they  may  be  imme- 
diately bolted  to  their  place.     When  the  lamp  is  inserted  and  the  necessary  con- 
nections are  made  to  the  supply  wires  the  projector  is  ready  to  operate. 

2.  For  pilot-house  control  projectors,  select  a  desirable  position  on  the  house 
roof  for  the  location  of  the  projector,  and  cut  a  hole  through  the  roof  nearly  the 
diameter  of  the  inside  of  the  low  base ;  disconnect  the  handle  and  bow  from  the 
lower  end  of  the  rod  and  shell,  and  bolt  the  projector  over  the  hole  in  the  roof, 
using  a  gasket  between  the  base  and  the  roof  to  keep  out  water.     The  arrow- 
head on  the  base  should  point  aft.     When  the  projector  is  in  place,  the  bow  and 
handle  can  be  replaced,  and  care  should  be  taken  to  see  that  the  handle  points 
in  the  opposite  direction  from  the  beam  of  light ;  for  example,  when  the  beam 
is  thrown  forward  the  handle  should  point  aft.     The  studs  and  terminals  are 
marked  +  and  — .     The  operating  mechanism  of  the  rope  control  consists  of  two 
small  drums  which  are  connected  to  the  operating  drums  on  the  projector  by 
ropes. 

3.  The  E.  C.  projector,  mounted  upon  a  low  truck,  stands  by  itself  under  can- 
vas cover  in  a  dry,  dust-proof,  sun-lighted  room,  from  which  it  may  be  run  out 
to  any  desired  point  within  1,000  feet  of  the  switch  board  and  dynamo,  and  is 
supplied  by  means  of  twin-core  cable.     The  controller  cable  should  permit  the 
controller  to  be  operated  at  150  feet  distance  from  the  projector.     The  connec- 
tions and  installation  appear  under  head  (F)  page  97. 


OF  THE 

UNIVERSITY 

OF 


SEARCH-LIGHT    PROJECTORS. 


93 


(E)  LAMP  MECHANISM  OF  ALL.  PROJECTORS. 

1.  Parts  of  lamp  mechanism  are  as  follows  (fig.  124) : 

A,  negative  carbon  holder.  J7,  fixed  nut  for  focusing  screw. 

B,  positive  carbon  holder.  -V,  stud  of  lamp  switch  for  cutting  out 

C,  clamping  screws  for  carbon  clamps.  feeding  magnet. 

D,  vertical  screw  positive  carbon  clamp.  O,  ratchet  and  pawl. 

E,  horizontal    screw   positive    carbon    P,  feeding  magnet  armature. 

clamp.  Q,  contact  of  circuit  breaker. 

F,  negative  carbon  support.  R,  adjusting  screw  for  ratchet  arm. 

G,  positive  carbon  support.  S,  starting  magnet. 
H,  lamp  frame.  T,  feeding. 

K,  main  lamp  contact  shoes.  U,  adjusting  spring  for  feeding  magnet. 

L,  hand  feed  screw. 

2.  Placing  tin'  lam j>  in  the  drum. — The  lamp  may  be  lifted  by  the  top  plate, 
but  it  should  never  be  lifted  by  the  carbon  supports,  as  the  strain  due  to  its 
weight  is  liable  to  spring  them  out  of  their  correct  position.     The  18-inch  and 
24-inch  projectors  have  obturators  which  prevent  carboning  the  lamps  before 
they  are  placed  in  the  drums.     The  drums  of  these  projectors  are,  however, 
sufficiently  large  to  readily  permit  adjustments  of  the  carbons  after  the  lamps 
are  in  place.     When  inserting  the  18-inch  or  24-inch  lamp  in  the  drum,  the 


125.  Obturator. 

shutters  of  the  obturator  should  be  opened  and  the  arc  magnet  turned  so  that 
the  opening  is  downward.  This  adjustment  may  be  made  after  removing  the 
pin  on  the  side.  The  lamp  may  now  be  placed  in  the  projector,  the  arc  magnet 
returned  to  its  proper  position,  and  the  shutter  of  the  obturator  closed. 

3  Carboning  the  lamp. — The  carbons  are  placed  horizontally  in  the  focal 
axis  of  the  mirror.  The  positive  carbon  should  have  its  crater  toward  the 
mirror.  The  projectors  are  intended  for  use  on  circuits  of  110  volts,  and  a  regu- 
lating rheostat  is  furnished  with  each  projector  to  provide  the  necessary  voltage 
at  the  lamp  terminals.  The  rheostat  is  shipped  to  conform  with  the  voltage  of 
the  circuit,  which  should  be  stated  when  the  projector  is  ordered.  To  obtain 
the  best  results,  the  rheostat  should  be  adjusted  once  for  all  according  to  the 
volts  and  amperes  given  in  the  table  at  the  head  of  this  article. 


94  HANDBOOK    FOR    ELECTRICIANS. 

The  carbons  must  be  of  the  best  quality.  Hardtmuth  and  Schmeltzer  carbons 
are  satisfactory. 

In  placing  the  carbons  in  the  lamp,  separate  the  carbon  holders  as  far  as  pos- 
sible by  turning  the  feed  screw.  The  larger,  or  positive  carbon,  shoukf  be 
placed  in  the  clamp  nearest  the  ratchet  mechanism.  Adjust  the  carbons  so  that 
they  come  in  contact  with  each  other  exactly  above  the  white  line  on  top  of  the 
lamp.  This  line  should  coincide  with  the  white  line  inside  of  the  drum  when 
the  lamp  is  in  place.  The  carbons  should  also  be  adjusted  so  that  their  axes 
coincide.  Readjustment  of  the  carbons  is  necessary  from  time  to  time  so  as  to 
keep  the  crater  in  the  center  of  the  positive  carbon  and  not  allow  it  to  burn 
off  at  the  edge.  If  the  crater  becomes  displaced  on  account  of  impurities  in 
the  carbons,  the  carbons  should  be  readjusted  so  as  to  form  a  new  crater  in  the 
correct  position. 

4..  Operating  the  lamp  mecJicnuant  (figs.  126-7-8). — (a)  After  closing  the  main 
switch,  the  carbons  will  begin  to  feed  toward  each  other  until  they  touch,  and 
the  circuit  will  be  completed,  so  that  the  starting  magnet  will  draw  the  carbons 
apart  about  £  inch,  thus  striking  the  arc.  As  the  carbons  burn  away  the  arc 
becomes  longer  and  the  voltage  across  the  arc  increases.  More  current  is  thus 
compelled  to  pass  through  the  feeding  magnet  in  shunt  with  the  arc.  Its  armature 
immediately  breaks  the  circuit  through  the  coil  and  then  flies  back,  thus  mov- 
ing the  pawl  and  turning  the  ratchet  at  the  end  of  the  feed  screw. 

STARTING  MAGNET 

negative  Cat-bon  Carrier  Posit! 


Coils  for-  tne  starting  magnet  or  2.4'  lamps  ar-e 

connected  in  multiple  as  shown 

Coils  for  16130  »nd  36  lamps  are  connected  in  series. 


Contact  Snoe 


FEEDING  MAGNET 

Feeding  magnet  Cir-cu 


126.  Connections  of  18,  24,  30  and  36  inch  Automatic  Projector  Lamps. 

(b)  Focusing  tlte  lump. — After  starting  the  lamp,  focus  it  with  relation  to 
the  mirror  by  watching  the  rays.     When  the  rays  diverge,  the  arc  is  too  near  the 
mirror,  and  when  they  cross  at  some  distance  from  the  projector,  the  arc  is  too 
far  from  the  mirror.     The  proper  distance  between  the  arc  and  mirror  is 
obtained  by  moving  the  lamp  backward  and  forward  by  means  of  the  focusing 
screw.     The  light  will  not  be  satisfactory  unless  the  lamp  is  in  focus,  and  the 
operator  must,  therefore,  never  neglect  to  focus  the  lamp  before  using  the 
projector. 

(c)  When  the  arc  is  in  the  focus  of  the  mirror  the  image  of  the  carbons  will 
fall  on  the  ground  glass  of  the  vertical  peep  sight  (see  S,  fig.  128a)  so  as  to  sln>\v 
the  positive  or  larger  carbon  just  touching  the  vertical  line. 

(d)  In  the  18-inch  and  24-inch  projectors  the  focusing  screw  is  arranged  to 
screw  into  the  back  of  the  lamp  and  is  fastened  permanently  to  the  projector. 
The. lamp  should,  therefore,  be  so  placed  that  the  thread  of  the  focusing  screw 
catches  and  draws  the  lamp  into  focn>. 


SEARCH-LIGHT    PROJECTORS. 


95 


(e)  If  the  carbons  are  placed  as  described  and  the  lamp  placed  in  the  drum  so 
that  the  two  lines  referred  to  under  "Carboning  the  Lamp"  coincide,  the  arc 
will  be  so  nearly  in  focus  that  but  little  adjustment  will  be  necessary. 

(/)  The  lamp  should  be  kept  clean  and  free  from  carbon  dust  which  occa- 
sionally drops  from  the  carbons  while  burning. 

(g)  The  feed  screws  may  be  oiled  when  necessary  with  a  small  amount  of 
good  clock  oil,  but  care  should  be  taken  to  carefully  wipe  them  after  oiling,  as 
otherwise  small  particles  of  carbon  dust  may  adhere  and  cut  the  thread.  The 
carbon  carriages  and  parts  carrying  current  should  never  be  oiled. 

(h)  Asa  few  slight  changes  will  be  found  in  lamps  constructed  in  different 
years,  reference  is  made  to  figs.  127-8,  alike  lettered,  from  which  the  plan  of  oper- 
ation of  all  will  be  readily  understood. 


M 


----F 


127.  G.  E.  Search  Light. 

The  springs  A  take  current  from  leads  to  the  contact  rings  of  the  pedestal, 
the  path  of  the  current  being  shown  in  fig.  128. 

The  carbons  are  secured  in  clamps  B  on  supports  C,  the  supports  being  mova- 
ble in  guides  of  the  frame  and  controlled  by  screw-bars  D  and  E.  The  larger 
clamp  is  for  the  positive  carbon,  in  which  the  crater  is  formed  and  which  will 
therefore  be  the  farther  clamp  from  the  projector  mirror.  F  is  the  automatic 
feed,  shunted  from  the  lamp  leads,  having  an  electro-magnet  G,  which  controls 
the  armature  H,  and  which  in  turn  operates  the  screw-bars  D  and  E  through  a 
pawl-ratchet  F,  and  gearing  J,  when  the  voltage  in  the  magnet  is  above  50  to 
52  volts.  K  is  the  series-striking  arc  magnet  which  operates  only  when  the  cur- 
rent is  much  in  excess  of  that  required  for  the  lamp.  A  lug  on  its  armature 
embraces  the  screw-bar  D  between  two  collars.  The  screw  has  a  small  play  at 
L  which  is  independent  of  the  control  of  the  automatic  feed.  Owing  to  the  gear, 
the  screw-bar  D  revolves  but  one-half  as  fast  as  E.  E  can  also  be  turned  by  a 
removable  crank  socket  wrench  at  T. 

The  method  of  operation  is  this:  The  carbons  are  first  adjusted  by  the  crank 
wrench  to  a  separating  distance  of  about  half  an  inch.  The  automatic  switch 
M  should  now  be  closed.  The  main  switch  is  closed  next,  and,  as  no  current 
can  pass  until  the  carbons  touch,  the  voltage  across  the  carbons  up  to  that 
moment  must  be  110  volts.  The  shunt  magnet  (called  the  feed)  commences  to 
vibrate,  the  voltage  being  greater  than  52  volts,  and  feeds  the  carbons  together 
by  means  of  the  pawl  and  the  gear  wheels  of  the  screw  bars.  When  the  carbons 
touch  a  heavy  momentary  current  passes  (since  the  resistance  is  small  and  volt- 
age at  110),  the  armature  of  the  striking  arc  magnet  is  attracted,  pushes  back 


96 


HANDBOOK   FOR   ELECTRICIANS. 


the  negative  screw  bar  and  forms  ("strikes")  the  arc.  The  resistance  of  the 
rheostat,  in  circuit  when  first  set  up,  causes  a  drop  of  50  to  60  volts  as  soon  as 
the  current  passes,  and  should  be  adjusted  by  the  lever  to  the  voltage  necessary 
for  running  the  lamp  without  flaming  and  hissing.  The  voltage  required  in 
practice  is  usually  from  45  to  49  volts ;  the  feed  will  frequently  operate  at  50 
volts.  The  working  current  for  the  lamp  varies  with  the  size  of  the  lamp  and, 
incidentally,  with  the  size  of  the  carbons ;  it  is  as  great  as  75  to  90  amperes  for 
the  30-inch  projectors,  and  from  25  to  35  amperes  for  the  18-inch  type. 

There  is  often  some  flaming  of  the  carbons  which  can  not  be  controlled  by  the 
rheostat ;  it  is  unimportant  except  from  the  fact  that  it  decreases  the  intensity 

of  the  light ;  it  will  usually  disap- 
pear of  itself.  Horizontal  lamps 
have  a  tendency  to  flame  at  the 
upper  edge  of  the  crater,  thereby 
forming  the  crater  on  the  upper 
edge  of  the  positive  carbon  and  dis- 
torting the  reflection ;  this  tendency 
is  corrected  in  some  projectors  by  a 
horseshoe  magnet,  attached  to  the 
diaphragm  in  the  projector,  which 
draws  down  the  arc  by  magnetic 
attraction. 

Some  hissing  will  occur  when 
starting  up,  especially  with  new 
carbons,  and  the  lamp  will  not  quiet 
down  until  a  good  crater  has  been 
formed  in  the  positive  carbon.  This 
can  be  obviated  by  reaming  out  a 
crater  in  the  positive  carbon  with  a 
penknife  before  putting  it  in  the 
clamp. 

Flaming  and  hissing  are  promoted 
by  inferior  carbons  and  are  much 
increased  if  the  carbons  have  ab- 
sorbed oil.  Those  now  provided  are 
of  the  Schmeltzer  manufacture  and 
are  very  homogeneous ;  the  positive 
carbon  is  usually  bored  axially  and 
cored  with  a  soft  carbon,  which 
materially  assists  in  maintaining 
a  good  crater.  Negative  carbons 
are  sometimes  cored,  but  it  is  an 


128.  Lamp  Details  Showing  Method  of 
Operation. 


open  question  whether  this  expe- 
dient does  not  conduce  to  the  forma- 
tion of  mushrooms.  Carbons  are 
packed  in  tins  and  should  be  kept  covered  in  a  dry  place,  as  they  readily  absorb 
moisture. 

The  momentary  current  of  short  circuit,  when  the  carbons  touch,  is  ordinarily 
heavy  and  quite  sufficient  to  throw  the  pointer  of  the  ammeter  clear  across  the 
scale  and  against  the  stops ;  it  need  occasion  no  apprehension  if  it  does  not  con- 
tinue ;  if  it  does,  the  switch  at  the  switch  board  should  be  quickly  opened.  This 
current  may  be  as  much  as  50  per  cent  above  the  working  current. 

Any  abnormal  current  of  the  searchlight  ammeter  is  usually  traceable  to 
either  a  mushroom  on  the  negative  carbon  or  careless  handling  of  the  socket 
wrench.  In  most  cases  of  fusing  of  the  contact  plungers  in  the  pedestal  there 
is  direct  evidence  of  an  attempt  to  regulate  the  feed  by  hand  when  the  auto- 
matic gear  is  switched  on.  If  the  lamp  does  not  feed,  it  is  for  the  reason  that 
there  has  been  a  burn  out,  or  that  the  lamp  itself  is  not  clean,  and  in  90  per  cent 
of  the  cases  dirt  is  the  cause ;  any  attempt  to  remedy  matters  by  use  of  a  socket 
wrench,  while  the  current  is  on,  is  quite  sure  to  short-circuit  the  lamp  and  pro- 
duce overload. 

The  mushroom  appears  as  a  small  protuberance  on  the  end  of  a  carbon  and  is 
of  a  pasty  consistency.  It  can  readily  be  removed  by  the  end  of  a  screw-driver. 
Ordinary  attention  to  the  working  of  a  lamp  should  guard  against  its  forma- 
tion. It  will  cause  the  carbons  to  adhere. 


SEARCH-LIGHT    PROJECTORS. 


97 


(F)  CONNECTIONS  AND  INSTALLATION  OF  IT.  S.  ELECTRIC 
CONTROLLED   PROJECTOR. 


128a.  Parts  of  Projector  and  Controller. 


1.  Parts  of  projector  and  controller  are  as  follows: 


A,  hand  star  wheel  for  slow  vertical  movement. 

J5,  wheel  for  throwing  out  split  nut  used  for  connect- 
ing or  disconnecting  the  drum  from  the  base 
mechanism. 

C,  wheel  for  slow  horizontal  movement. 

I>,  hand  star  wheel  for  clamping  turntable  to  center 
pin  for  electrical  control. 

E,  wood  handles  on  drum  for  moving  drum  by  hand. 

F,  hand  wheel  for  clamping  hand  star  wheel  A  when 
electric  control  is  used. 

G,  controller  switch. 
H,  controller  handle. 
7,  controller  fuse  box. 

J",  controller  coupling  for  connecting  cable  from  the 

projector. 
K,  focusing  screw 


L,  socket  for  inserting  wrench  to  operate  lamp  switch 
used  for  cutting  out  feeding  magnet. 

M,  socket  for  inserting  wrench  when  feeding  by  hand. 

N,  door  used  for  adjusting  the  carbons  and  for  clean- 
ing the  front  door. 

O,  door  used  when  carbons  are  to  be  adjusted  or 
changed. 

P,  front  door. 

Q,  door  used  when  adjusting  negative  carbons  or 
cleaning  the  mirror. 

R,  horizontal  peepsights. 

8,  vertical  peepsights. 

T,  sliding  case  to  be  opened  when  lamp  mechanism 
is  to  be  inspected. 

U,  projector  main  switch. 

F,  latches  for  fastening  base  sheeting. 

W,  base  sheeting. 


2.  Projector  with  base  sheeting  removed  (fig.  129).     The  numbers  indicate 
the  places  for  oiling : 

The  worm  1  at  the  back  of  each  motor ;  the  two  worm  trays  ought  always 
to  contain  enough  oil  to  allow  the  worm  to  bathe  in  it ;  the  horizontal  worm 
wheel  at  2 ;  the  vertical  countershaft  at  3  and  the  tread  wheel  at  4,  by  unscrew- 
ing the  plug  and  oiling  through  the  hole  while  turning  the  turntable  one  com- 
plete revolution,  so  as  to  distribute  oil  along  the  groove  in  the  tread  wheel  ring ; 
the  internal  parts  of  the  mechanism  are  oiled  at  5,  filling  the  grooves  around 
the  center  rods ;  the  crosshead  at  6  and  7 ;  the  vertical  training  at  8,  by  loosening 
the  clutch  and  putting  the  oil  inside,  and  the  trunnions  at  9.  The  controller  is 
oiled  at  10.  Any  extra  oil  must  be  wiped  off  so  as  not  to  allow  dust  to  stick  to  it. 

3.  Connections  of  E.  C.  projector  and  controller  are  shown  in  fig.  130. 

1714—7 


98 


HANDBOOK    FOR    ELECTRICIANS. 


6 — -m-V 


3 


129.  Training  Mechanism  Controller  and  Cable. 

4.  Wiring  diagrams. — Fig.  130  shows  searchlight  connections  except  switch- 
board and  lamp  mechanism;  fig.  132.  switchboard  and  the  vertical  training 
mechanism  shifted  in  position  for  clearness,  and  fig.  131  all  important  connec- 
tions when  both  the  horizontal  A  B  and  vertical  A'  B'  training  slides  stand  at 
their  middle  positions  and  neither  motor  runs. 

In  the  horizontal  training  mechanism  (all  figs. )  A  and  B  are  separate,  insu- 
lated, metal  plates  on  one  block  which  slide  together  to  the  right  or  left  for  a 
total  distance  equal  to  one-half  the  width  of  the  plate  according  as  the  con- 
troller's handle  attached  to  the  block  is  turned  right  or  left.  A  loses  contact 
with  the  left  brush  X  as  it  first  moves  to  the  right,  or  with  the  right-hand 
brush  Y  as  it  first  moves  to  the  left,  and  with  either  motion  it  slides  succes- 
sively into  contact  with  the  five  insulated  brass  fingers  which  press  against  it 
and  which  are  the  terminals  of  rheostat  coils.  Resistance  is  thus  thrown  out 
and  into  the  armature  circuit  of  the  motor  which  trains  the  projector  horizon- 
tally. Plate  B,  always  in  contact  with  its  middle  brush  N,  moves  with  A  and, 
like  it,  loses  contact  with  its  left  or  right  brush,  M  or  O. 

In  a  similar  manner,  insulated  plates  A'  and  B,  of  the  "vertical  training" 
mechanism,  lose  and  make  contacts  with  their  corresponding  brushes  by  being 
moved  up  or  down  (fig.  130  alone  shows  right  position)  by  means  of  the  same 
controller  handle  as  above. 

A',  like  A,  slides  in  and  out  of  contact,  successively,  with  its  five  brass  fingers, 
which  thus  throw  rheostat  coils  out  of  and  into  the  armature  circuit  of  the 
motor  which  trains  the  projector  in  a  vertical  direction. 

The  "controller  switch"  being  closed,  the  shunt  fields  of  both  motors  are 
excited.  Either  motor  is  started  by  turning  the  controller  handle  right  or  left, 
up  or  down,  sufficiently  to  slide  A  B  or  A  B'  away  from  their  respective  brushes 
on  one  side.  If  to  the  right  in  the  horizontal  training  mechanism,  the  current 
flows  through  the  "horizontal  training"  motor's  armature  in  one  direction;  if 
to  the  left,  in  the  opposite  direction — thus  reversing  the  motor's  motion. 


SEARCH-LIGHT   PROJECTORS. 


99 


Horizontal  Training          SwrbcK 


Vertical  Training 


Controller 


U*        UUUL^UJiLJ^- 


130.  For  Use  in  Assembling. 

Likewise-  for  the  vertical  training  mechanism  and 
motor.  While  the  slides  A  B,  A'  B~  are  at  the 
mid  positions  shown,  all  rheostat  coils  are  in  the 
motor  armatures'  circuits  which  are  short-circuited 
and  can  not  therefore  revolve.  But  when  A  B  or 
A'  B'  is  moved  in  either  direction  the  short  cir- 
cuit is  opened  and  the  coils  are  gradually  cut  out 
and  the  speed  is  increased.  There  are  four  steps 
and  either  motor  has  accordingly  four  different 
speeds. 

5.  Installing. — For  either   hand   or 
electric  control  the  current  should  be 
led  directly  from  the  switch  board  in 
the  dynamo  room  to  the  double -pole 
switch  inside  the  base  of  the  projector, 
both  conductors  going  through  insu- 
lated holes    in  the  base-plate  of    the    projector. 
Facing  the  switch  the  positive  pole  is  to  the  left, 
and  the  negative  to  the  right. 

The  dead  resistance  should  be  placed  near  the 
switchboard,  and  in  circuit  with  the  positive  con- 
ductor. This  method  of  connecting  is  essential 
on  account  of  connections  to  the  motor  for  electric 
control.  The  size  of  the  conductors  varies  with 
the  size  of  the  projector  used,  and  is  determined 
by  the  amperes  per  circular  mil  allowed  by  specifi- 
cations. 

A  third  wire  leading  from  the  dynamo  room  to 
the  projector  base  is  connected  at  the  positive  pro- 
jector switch  on  the  switchboard,  and  at  the  other 
end  to  contact  No.  3  on  the  connection  board 
inside  the  base  of  the  projector.  The  third  wire  ^^^SffijSSSfiSSS: 


100 


HANDBOOK   FOR   ELECTRICIANS. 


is  used  in  order  to  get  full  voltage  at  motor  terminals.  Its  cross  section 
will  vary  with  the  length  of  the  circuit,  but  the  total  resistance  must  not  measure 
more  than  .05  ohm.  The  negative  conductor  of  the  lamp  circuit  is  used  for  the 
return,  and  is  connected  at  the  factory  from  contact  No.  4  on  connection  board 
to  the  negative  side  of  the  main  switch.  Seven  wires  connect  the  contacts  of 


fo" 

V£££^.-~  -~"Tf'  -V.T-T. 

X^V; 

/     x:>'\ 

3 

<S 

f«5 

£=£ 
J  - 

^\  .-^      "*^N 

the  connection  board  inside  the  base  of  the  projector  and  those  of  the  controller 
receptacle.     The  contacts  are  numbered  both  on  the  connection  board  and  on  the 

. 

receptacle,  and  should  be  connected  accordingly.  The  controller  receptacle 
should  be  placed  within  a  radius  of  20  feet  of  the  controller.  The  required  size 
of  the  seven  conductors  varies  according  to  the  length  of  the  circuit.  The 


SEARCH-LIGHT   PROJECTORS. 


101 


following  table  gives  the  maximum  allowable  resistance  for  each  wire,  and  the 
size  of  wire  for  circuits  of  various  lengths : 


Number  of 
Conductor. 

Si/.-  of  Wiiv,   li.   &  S.  Gau-r. 

Maximum 
Resistance, 
Ohms. 

•>n  Feet. 

100  Feet. 

ir.n  F.M-t. 

1 

14 

11 

9 

.14 

2 

14 

11 

9 

.14 

3 

11 

8 

6 

.07 

4 

10 

7 

5 

.05 

5 

14 

14 

14 

.62 

6 

14 

11 

9 

.14 

7 

14 

11 

9 

.14 

The  search-light  barrel  should  move  with  the  controller  handle  as  if  this  were 
fixed  to  the  rear  part  of  the  barrel.  The  farther  the  controller  handle  is  moved, 
right  or  left,  up  or  down,  the  more  rapidly  the  projector  should  travel.  Small 
motion  can  be  gotten  by  momentarily  striking,  by  means  of  the  handle,  a  finger 
of  the  training  mechanism. 

(G)    OPERATING  THE  E.    C.    SEARCH-LIGHT  PROJECTOR. 

1.  The  key  to  good  search  light  operation  and  management  is  thorough  cleanli- 
ness in  all  the  parts  and  frequent  opportunity  for  practice  by  those  to  be  called  upon. 

2.  The  mirror  will  spot  or  frost  in  time  if  not  kept  in  a  dry  place.     The  action 
is  hastened  by  damp  and  by  the  practice  of  exposing  it  to  the  rays  of  the  sun 
while  drying  out  the  barrel.     The  life  of  a  projector  is  shortened  one-half  from 
lack  of  care. 

3.  Dust     then A H  r E-™ 


mirror  surface  ! 


gently  with  a  soft 
duster — do  not 
clean  by  rubbing. 

4.  Set  the  car- 
bons before  oper- 
ation and  permit 
no    use    of    the 
wrench  except  in 
focusing ;  there  is 
rarely  any  occa- 
sion for  its  use  on 
the     screw     bar 
after  the  lamp  is 
in  operation. 

5.  Every    pro- 
jector     front 
should  be  fitted 
with    an    extra 
outside     door 


134. 


made  of  perforated  fiber  for  the  protection  of  the  front  glasses. 

6.  Diverging  lenses  are  plano-convex  in  the  horizontal  plane  only.     The  door 
is  made  in  strips  similar  to  that  having  the  plain  glass,  each  strip  being  a  plano- 
convex lens. 

7.  The  parabolic  surface  projector  which  is  gradually  replacing  all  other 
forms,  lights  up  a  distant  object  with  greater  brightness  and  distinctness. 

8.  The  rheostat  (fig.  134)  must  be  able  to  carry  the  full  current  and  have 
sufficient  resistance  to  cause  a  drop  (C  X  R)  of  30  volts  from  an  80-yolt  supply, 
or  60  volts  from  a  110-volt  supply;  this  includes  an  adjustable  resistance  for  a 
range  of  10  to  20  volts. 

9.  While  hot  the  reflector  should  not  be  moved  nor  its  door  opened. 

10.  The  two  carbons  should  lie  in  a  straight  line,  the  positive  and  larger  is  the 
farther  from  the  mirror ;  if  new  or  deformed  a  crater  should  be  reamed  out. 

11.  Waterproof    covers  are  always  provided  for  projector,   controller  and 
rheostat. 

12.  Cable  couplings  are  liable  to  give  trouble  from  moisture  in  spite  of  the 
water-tight  gaskets.     Use  only  two  end  couplings ;  splice  and  insulate  all  other 
joints;  cover  with  painted  canvas  and  keep  them  as  dry  as  possible. 

13.  Fusing  may  occur  in  the  contact  plungers  of  the  pedestal  whose  office  is  to 
connect  the  contact  rings  of  the  base  with  the  main  contacts  for  the  lamp.    When 


102 


HANDBOOK   FOR   ELECTRICIANS. 


this  fusing  takes  place  the  pedestal  becomes  locked  and  can  not  revolve.  It  is 
commonly  caused  by  the  nonseparation  of  the  carbons,  either  from  failure  of 
the  mechanism  or  the  adherence  of  the  carbons  due  to  the  formation  of  a  mush- 
room on  the  negative  carbon.  The  remedy  is  to  increase  the  contact  area  and 
to  use  greater  care  in  operating. 

14.  For  signaling,  projectors  may  be  operated  by  hand  to  throw  the  beam 
against  the  sky  right,  left,  or  down ;  or  supplied  with  a  Venetian  shutter  in  front 
to  make  the  one  and  two  short  flashes  of  the  letters  of  the  alphabet. 

15.  A  good  line  of  sight  makes  3J  or  more  with  the  beam  at  the  object.     The 
blinding  effect  of  the  beam  is  small  at  7°  angle. 

16. .  On  a  clear,  dark  night,  the  60-inch  Schukert  projector  enables  the  naked  eye 
near  it  to  see  a  light  object  30  feet  high  by  20  feet  wide  at  6  miles  distance ;  but  if 
dark  it  can  be  seen  at  this  distance  only  by  the  aid  of  a  strong  glass,  becoming 
visible  to  the  naked  eye  at  4  miles.  The  36-inch  parabolic  mirror  permits  the 
light  object  above  to  be  seen  at  4  miles,  but  if  dark,  only  by  the  aid  of  the  glass. 

17.  The  generating  set  requires  one  electrician  and  assistant ;  the  projector,  one 
electrician  and  attendant ;  the  cable,  one  attendant ;  observers,  each  with  a  signal 
man  if  at  a  distance.     The  last-named  carries  a  lantern  darkened  on  the  side 
toward  ttie  enemy.     The  new  observer  sees  little  or  nothing.     To  him  objects 
appear  unnatural  at  night.     He  has  not  even  a  mariner's  experience,  and  he  inno- 
cently reports  the  searchlight  a  failure,  while  the  practiced  observer  will  obtain 

food  results.  This  one  takes  a  position  on  either  side  of  the  beam  and  uses  a 
eld  glass  having  the  largest  possible  object  lenses,  low  magnifying  power,  and 
no  diaphragm.  He  forms  some  conception  of  the  objective  and  notes  all  con- 
spicuous details  in  the  vicinity.  It  is  important  to  find  near  the  objective  one 
or  more  points  which  are  fixed,  light  colored  and  known,  such  as  a  house,  beacon 
or  shore,  In  order  to  direct  the  beam  upon  it  quickly  and  then  upon  the  objective. 
Well  defined  shadows  caused  by  impurities  in  the  atmosphere  should  not  be 
taken  for  dark  objects.  Moonlight  is  a  favorable  circumstance.  Mist  or  smoke, 
however  thin,  is  unfavorable.  Training  and  continued  practice  are  indispensable. 

18.  Degrees  of  illumination  of  projectors: 


MIRROR. 

Distance  i7i 
yards. 

Diameter  of 
beam  in 
yards. 

Diameter  of 
spot  in 
yards. 

Coefficient  of 
transparency. 

Times  illumina- 
tion of  full  moon 
at  zenith. 

36"  Spherical,   C  ==  100  ) 

3,300 

4,400 

120 
160 

90 
110 

0.8 
0.7 

40 
20 

5,-500 

190 

140 

0.66 

12 

60"  Spherical,   C  =  180  1 

3,300 
4,400 

100 
130 

75 
100 

0.8 
0.7 

100 
55 

5,500 

165 

125 

0.66 

33 

36"    Parabolic,   C   =    130 

7,000 

360 

300 

0.7 

15 

amperes. 

60"    Parabolic,   C   =   150 

10,000 

510 

430 

.7 

20 

amperes. 

19.  The  projector,  readily  movable  to  any  desired  point  within  1,000  feet  of 
the  generator,  is  placed  wholly  apart  from  the  works,  more  than  100  feet  from 
the  nearest  heavy  gun,  as  near  as  practicable  to  the  area  to  be  watched,  not 
higher  than  is  sufficient  to  overcome  the  earth's  curvature,  and  in  such  position 
that  objects  may  not  obstruct  the  beam.     Before  it  is  lighted  in  the  enemy's 
presence,  it  should  be  elevated  to  guard  against  illuminating  objects  in  its  own 
vicinity.     After  it  is  in  working  order,  the  screen,  if  any,  is  removed  and  the 
beam  is  gradually  depressed  to  the  horizon  while  moving  to  the  right  and  left  in 
exploration. 

20.  The  probability  of  a  60-inch  projector  being  hit  while  in  operation  at 
night  by  an  expert  marksman  on  land  at  a  half  mile  distance  is  less  than  ^. 
The  danger  to  projectors  from  ship's  fire  from  unstable  mounts  at  the  usual 
distance  is  therefore  quite  small.     It  will  lessen  the  accuracy  of  the  enemy's 
shots  to  extinguish  the  lamp  occasionally  or  to  move  it  quickly  to  some  other 
point.     The  only  special  protection  which  can  be  given  or  will  be  required  is  the 
same  as  for  all  guns — a  thick  earth  parapet  reaching  to  the  level  of  the  lower 
side  of  the  barrel.     The  largest  search  light  constructed  has  a  mirror  6i  feet  in 
diameter  and  an  illuminating  power  of  3  X  109  candles. 

(H)   TRANSPORTABLE   SEARCH-LIGHT  EQUIPMENT. 

Four  sets  (figs.  135-6)  were  ordered  in  the  first  preparations  for  the  use  of 
the  army  in  Cuba  but  could  not  be  delivered  by  the  largest  American  electrical 
firm  using  all  of  its  resources  to  complete  them  until  four  months  after  the 
necessity  for  them  had  passed. 


137.  Keyboard  for  Night  Signal  set. 


X.— GENERAL  ELECTRIC  COMPANY'S  NIGHT-SIGNAL  SETS 
AND  TRUCK-LIGHT  CONTROLLERS. 


(A) 


SETS. 


Night-signal  sets  include  four  parts,  namely:  keyboard,  cable,  lanterns,  and 
ladder. 

1.  Keyboard.  —  The  keyboard  consists  of  a  dial  and  operating  handle  mounted 
on  a  water-tight  box  containing  the  mechanism  for  connecting  the  lamps  in 
various  combinations.  The  keyboard  is  illuminated  by  an  incandescent  lamp 
supported  on  a  goose  neck,  and  the  box  has  receptacles  on  the  back  for  the  line 
and  the  lantern  cables.  The  mechanism  consists  of  a  central  rotating  stud  with 
eight  contacts  which  rest  against  eight  semicircular  plates.  Each  plate  is  made 
up  of  insulating  sections  of  hard  rubber  and  metal  sections  which  connect  with 
a  lamp  in  one  of  the  lanterns.  Obviously,  when  one  of  the  contacts  of  the  rotat- 
ing stud  rests  on  an  insulating  section,  the  circuit  through  the  lamp  is  broken  ; 
when  on  a  metal  section,  the  circuit  is  closed.  When  the  pointer  is  turned  to 


138.  Mechanism  of  Keyboard. 

the  position  on  the  dial  corresponding  to  the  desired  signal,  some  contacts  rest 
on  the  hard  rubber  sections  and  others  on  the  metal  sections,  thus  connecting 
into  circuit  a  certain  combination  of  lamps.  The  lamps  are  not  actually  lighted, 
however,  until  the  knife  switch  on  the  rotating  stud  is  closed  by  swinging  the 
knob  of  the  handle  down  toward  the  operator. 

2.  Connections. — Current  is  supplied  to  the  keyboard  through  two  line  plugs, 
one  of  which  is  connected  to  the  central  contact  in  the  lantern  cable  receptacle, 
and  the  other,  by  means  of  a  brush,  to  the  knife  switch  on  the  central  stud. 
Each  semicircular  plate  is  connected  to  a  contact  in  the  lantern  cable  recepta- 
cle, into  which  a  plug  is  fitted  to  establish  connection  with  the  lamps  through 
the  lamp  cable. 

The  cable  is  made  up  of  sixteen  conductors.  One  end  of  each  conductor  is 
connected  to  a  lamp,  and  the  other  end  to  the  plug  which  fits  into  the  recepta- 
cle on  the  keyboard.  Eight  conductors  run  from  the  eight  outside  contacts  of 
the  plug  to  the  eight  lamps,  and  the  other  eight  conductors  form  the  return 
from  the  lamps  and  are  connected  to  the  central  contact  of  the  plug.  When 

(103) 


104 


HANDBOOK    FOR    ELECTRICIANS. 


lamps  are  lighted,  the  current  flows  as  follows:  From  the  generator  to  the  line 
receptacle  on  the  box,  to  the  contact  ring,  to  the  switch,  to  the  plunger  con- 
tacts, to  the  semicircular  plates,  to  the  cable,  to  the  lanterns,  back  to  the  cable, 
to  the  central  contact  of  the  receptacle  on  the  box,  to  the  line  receptacle  on  the 
box,  to  the  generator. 

The  circuits  are  shown  in  detail  in  the  accompanying  diagram  ( 140) .  The  plug 
and  receptacle  are  made  water-tight  by  means  of  a  soft  rubber  gasket,  and  the 
sixteen  cables  from  the  plug  pass  through  another  gasket  in  the  gland  which 
makes  a  tight  joint  by  compressing  the  soft  rubber  around  them. 


139.  Keyboard,  Showing  Attaching  Plug  and  Receptacle. 

3.  Lanterns  and  ladder. — Each  of  the  four  lanterns  has  two  compartments, 
one  with  a  red  globe,  and  the  other  \yith  a  white  globe.  The  wires  pass  through 
water-tight  stuffing  boxes  in  caps  which  screw  on  each  end  of  the  lantern  with  a 
gasket  and  support  standard  lamps  and  sockets. 

The  ladder  is  made  up  of  galvanized-iroii  wires  with  metal  cross  pieces  from 
which  the  lanterns  are  swung. 

(B)  OPERATION. 

After  the  ladder,  lanterns,  and  keyboard  are  in  place  they  may  be  connected 
as  follows : 

Connections  to  the  line  should  go  to  the  two  small  outside  receptacles  on  the 
back  of  the  keyboard  box,  and  the  plug  on  the  end  of  the  lantern  cable  should  be 
inserted  in  the  receptacle  between  the  line  receptacles.  This  plug  can  be 
inserted  only  one  way,  as  the  receptacle  has  a  pin  which  must  fit  into  a  slot  on 
the  plug.  After  the  plug  is  inserted,  the  nut  D  (see  fig.  141)  should  be  screwed 
up  tightly  so  as  to  compress  the  soft  rubber  packing.  The  plug  should  never  be 
taken  from  the  receptacle  when  the  current  is  on,  as  the  sparking  is  apt  to 
injure  the  contacts,  particularly  the  center  one  which  carries  the  combined  cur- 
rent for  all  the  lamps.  Therefore,  before  removing  the  plug  see  that  the  knob 
on  the  handle  of  the  keyboard  is  in  an  upright  position.  To  operate  the  key- 
board, the  arm  with  the  pointer  can  be  swung  over  the  dial  to  the  combination 
required,  and  the  knob  depressed.  The  cam  actuated  by  the  knob  will  then 


NIGHT-SIGNAL   SETS   AND    TRUCK-LIGHT    CONTROLLERS. 


105 


engage  with  a  slot  so  that  the  arm  can  not  be  moved,  and  will  remain  in  this 
position  until  the  knob  has  been  raised  again.  This  arrangement  prevents  the 
display  of  false  signals.  If  pulsating  lights  are  required  they  may  be  produced 
by  means  of  the  pulsator  switch  on  the  central  shaft.  It  is  a  small  lever  which 


Insulation  Block: 
Plunder  Contaci. 

— "Pulsator  Switch. 


Operating  Switch. 

•Contact  Sprin.2- 
•  Conductor  Ring. 

SIGNAL  BOX 

140.  Diagram  of  Connections  of  Night-Signal  Set. 

extinguishes  the  lamps  in  the  upper  lantern  when  pushed  to  one  side  and  lights 
them  again  when  released.  The  lamp  socket  on  the  keyboard  is  provided  with 
a  switch,  and  when  not  in  use  the  lamp  should  be  extinguished  to  prevent 
excessive  heating  when  the  doors  of  the  cover  are  closed. 


141.  Receptacle— Plug. 

(C)    REPAIRS. 

The  soft -rubber  packings  used  about  the  couplings  and  cables  should  be  fre- 
quently examined  and  renewed  from  time  to  time,  as  the  rubber  becomes  hard 
and  partially  vulcanized  by  the  long  continued  compression  and  heat  from  the 
metal,  which  becomes  quite  hot  when  in  the  sun,  especially  in  tropical  climates. 
When  worn  out  the  cables  can  be  replaced,  one  conductor  at  a  time  or  all  at 
once.  To  replace  one  conductor,  unscrew  the  cap  at  the  lantern  and  disconnect 


106 


HANDBOOK   FOR   ELECTRICIANS. 


the  conductor  from  the  lamp  and  pull  the  cable  out  after  loosening  the  pack- 
ing in  the  gland.  Cut  the  seizing  about  the  cable  and  separate  the  defective 
conductor  as  far  as  the  cable  plug  on  the  box  and  cut  away  the  canvas  jacket. 
With  the  plug  removed  from  the  receptacle,  unscrew  part  A  and  slip  it  up 
the  cable  some  distance,  then  unscrew  part  B  after  taking  out  set  screw  C,  and 
work  the  gasket  back  on  the  cables  so  that  B  and  E  can  be  separated.  Pull 
B  and  E  apart  and  disconnect  the  defective  conductor  from  the  contact  and 
pull  it  out  through  the  gasket.  Unsolder  the  terminal  on  the  conductor,  and 
solder  it  to  a  new  conductor;  pass  the  new  conductor  through  A,  through  the 
gasket,  and  then  through  B,  and  connect  it  to  the  contact.  Screw  B  in  place, 
and  after  replacing  the  set  screw,  push  the  soft  rubber  gasket  down  into  the 
gland.  As  there  are  sixteen  conductors,  the  rubber  gasket  is  not  easily  inserted, 
but  by  pulling  on  one  conductor  at  a  time  and  changing  about,  the  gasket  can 
be  worked  into  place,  and  then  part  ^i  can  be  screwed  up  and  a  new  canvas  jacket 
put  on. 

To  connect  the  other  end  of  the  conductor  to  the  lamp  in  the  lantern,  pass  it 
through  the  rubber  gasket  in  the  gland  and  connect  it  to  the  lamp  socket. 
Screw  up  the  gasket  in  the  gland  tightly,  replace  the  cap  on  the  lantern  and 
screw  it  down  hard.  When  repairing  the  cable  in  this  manner  a  good  oppor- 
tunity is  offered  to  put  in  entirely  new  gaskets  all  around.  The  method  of  pro- 
cedure in  removing  the  entire  cable  is,  of  course,  the  same  as  in  removing  one 
strand.  The  cable  should  be  painted  occasionally  with  some  tar  compound  as  a 
preservative,  in  the  same  manner  as  standing  rigging. 

(D)  STANDARD   OUTFIT. 

The  complete  United  States  Government  signal  outfit  includes :  1  keyboard,  com- 
plete with  cover  and  lamp ;  1  ladder  and  cable  with  male  half  of  coupling ;  1  reel  of 
extra  single  conductor  cable ;  5  lanterns  (4  for  ladder  and  a  spare  lantern) ;  10  32- 
candlepower,  110-volt  lamps;  1  16-candlepower,  80-volt  lamp  for  keyboard;  1 
tool  box  containing  the  following — 2  fork  wrenches,  1  spanner,  1  grip  for  male 
plug  and  shell,  10  spare  gaskets  for  lantern  glands,  1  spare  gasket  for  coupling 
of  16  conductor  cables,  2  spare  gaskets  for  main  line  plug  contacts  on  keyboard, 
2  spare  washers  for  main  line  plug  contacts  on  keyboard,  10  spare  washers  for 
lantern  cap,  1  spare  washer  for  coupling,  16  spare  copper  terminals. 


TRUCK-LIGHT  CONTROLLERS. 


142.  Diagram  of  Connections  of  Truck-Light  Controller. 

The  controlling  switch  for  truck  lights  is  contained  in  a  metal  box  and  con- 
nected to  the  circuit  by  leads  passing  through  the  hollow  pedestal  on  which  the 
box  is  mounted.  The  handle  on  top  of  the  box  is  used  for  operating  the  switch, 


NIGHT-SIGNAL   SETS   AND   TRUCK-LIGHT    CONTROLLERS.          107 

and  tho  lamp  lighted  at  any  one  position  is  indicated  by  the  pointer.  The  light 
may  be  pulsated  by  moving  the  pulsator  button  on  the  side  of  the  box  in  and  out. 

When  connecting  the  truck-light  controlling  switches  follow  the  diagram  in 
fig.  142.  The  terminals  on  the  inside  of  the  box  are  marked  M  R,  M  W,  F  Rt 
F  W;  those  to  which  the  line  connections  are  made  are  marked  L. 

The  line  wires  should  be  connected  to  the  terminals  marked  L;  those  from  the 
' '  main  "  red  half  of  the  lantern  to  M  R;  from  ' '  main  "  white  to  M  W;  from  ' '  fore  " 
rec1  to  F  R,  and  from  "fore"  white  to  F  W. 

Terminals  are  provided  which  should  be  soldered  to  the  ends  of  the  wires  and 
fastened  to  the  contacts  with  screws. 

The  covers  on  the  sides  of  the  box  should  be  removed  every  three  months.  If 
the  contacts  are  discolored  they  should  be  polished,  and  any  irregularities  or 
burnt  places  should  be  smoothed  off  with  a  file. 

(F)  DIRECTIONS  FOR  THE  BOUGHTON  NIGHT-SIGNAL  SET. 

It  is  transported  in  three  boxes — keyboard,  cable,  lanterns. 

TO  ASSEMBLE. 

1.  Open  box  No.  1  and  remove  keyboard  and  secure  its  base  at  place  where  it 
is  to  stand  by  suitable  screws  or  bolts. 

2.  Open  box  No.  2  and  take  out  lantern  support  and  lay  same  along  the 
ground  with  its  upper  end  (shown  by  absence  of  electric  cable  which  depends 
from  the  lower  end)  near  the  foot  of  staff  from  which  it  is  to  hang. 

3.  Connect  the  electric  cable  which  depends  from  the  lower  end  of  the  wire 
cable  lantern  support  to  the  keyboard,  by  its  coupling,  and  screw  the  collar 
home.     Connect  keyboard  with  electric  current  of  emplacement,  through  the 
two  binding  posts  seen  on  under  surface  of  keyboard.     Wires  should  be  equal 
to  serve  sixteen  10  candlepower  lamps  at  once. 

4.  Unpack  box  No.  3  and  take  out  glass  lenses  for  lanterns,  four  red  and  four 
white,  carefully  dust  and  wipe  same  with  clean  cloth,  and  place  same  in  frames 
thus  making  four  double  lanterns  of  white  and  red  lenses,  white  above  and  red 
below. 

The  lantern  frames  are  made  ready  for  lenses  by  unscrewing  the  top  and  bot- 
tom nuts  of  the  four  side  bolts  which  make  the  lantern  frame,  when  the  top  or 
bottom  sockets  may  be  moved  up  or  down  ready  for  the  lens. 

The  mid-division  of  the  lantern  carries  the  electric  lamp  sockets,  and  sustains 
the  weight  of  the  double  lantern ;  it  is  clutched  and  bolted  to  the  larger  wire 
cable  and  is  not  to  be  moved. 

Rubber  gaskets  are  placed  between  each  end  of  each  lens  and  its  support, 
making  the  lantern  gas  and  water  tight. 

5.  Wipe  electric  lamps  with  clean  cloth,  push  lamps  to  mid-division  of  lantern, 
three  on  top  and  four  on  bottom.     Lanterns  are  opened  for  setting  lamps  in 
place  by  unscrewing  top  and  bottom  caps.     Replace  lantern  ends  by  screwing 
same  home. 

Test  electric  connections  of  each  lamp  of  each  lantern  from  keyboard.  See 
that  each  lamp  lights  promptly,  and  gives  its  light  in  full  candle  power. 
Lamps  failing  to  light  fully  are  broken  or  not  set  right  in  socket,  and  must  be 
replaced  or  properly  placed  in  socket. 

6.  Hoist  lantern  frame  to  place  on  mast  and  make  fast  to  outrigger,  back  stay 
and  below. 

7.  Place  pilot  light  in  its  socket  at  back  of  keyboard. 

TO  USE. 

The  keyboard  swings  on  the  base  in  an  arc  of  180°  in  order  that  the  operator 
may  face  the  point  signaled. 

To  swing  the  keyboard,  pull  the  stud  at  the  side  of  upper  part  of  base  and 
swing  the  keyboard  in  the  direction  desired.  The  swinging  device  is  self -lock- 
ing at  various  intermediate  points  of  its  arc,  by  means  of  the  stud  above 
mentioned 

The  telephotos  shows  the  signals,  letters  or  numerals  shown  on  the  top  of  the 
keys  of  the  keyboard  as  a  flash  signal  or  as  a  standing  signal  at  the  will  of  the 
operator. 

To  signal  by  flash  signal,  press  down  the  proper  letters  or  numerals  and  hold 
same  down,  five,  eight  or  ten  seconds,  according  to  the  ability  of  the  person 


108 


HANDBOOK   FOR   ELECTRICIANS. 


signaled  to  read  signals ;  upon  releasing  the  key,  the  signal  disappears  and  you 
are  ready  to  show  the  next.  But  one  signal  key  may  be  used  at  once,  to  avoid 
confusing  the  receiver  of  the  signal. 

The  pulsator  may  be  used  at  any  time  with  any  signal. 

To  make  a  standing  signal,  press  down  the  proper  key  as  before  and  give  the 
key  a  twist  to  the  left  and  it  will  stay  down.  As  long  as  the  key  is  down  its 
letter  or  signal  is  shown.  To  release  the  key,  give  the  same  a  twist  back  and  it 
will  rise  to  the  level  of  the  others,  and  its  signal  will  disappear. 

Before  sending  important  messages  one  should  be  familiar  with  the  keys, 
learn  what  letter  or  numeral  they  represent,  learn  the  pressure  needed  to  bring 
down  a  key,  the  time  required  for  a  signal  to  appear,  be  read  and  to  disappear, 
learn  the  use  of  the  pulsator,  and  the  interval. 

To  examine  the  contents  of  the  keyboard,  unscrew  brass  studs  around  outer 
margin  of  key  plate,  when  key  plate  may  be  lifted  out  of  place  and  all  contents 
of  keyboard  will  be  in  plain  reach  and  sight  and  so  simple  as  to  require  no 
explanation.  In  replacing  key  plate  see  that  its  rubber  gasket  is  in  place. 

When  not  in  use,  the  door  in  brass  cover  of  keyboard  should  be  pulled  down, 
and  the  telephotos  protected  by  a  canvas  cover. 

The  keyboard  being  hermetically  sealed,  might  in  some  climates  show  signs 
of  condensation  on  account  of  temperature  in  the  box  and  that  on  outside  not 
being  equal.  Should  this  ever  occur,  remove  the  keyboard  plate  and  take  small 
cork  in  bottom  of  box  out.  This  will  make  temperature  inside  and  outside 
alike. 


XI.— MISCELLANEOUS  APPARATUS. 


(A)   THE  FIRING  KEY. 

The  firing  key  is  a  small,  single-throw  knife  switch  with  spring  to  keep  the 
knife  normally  open,  with  an  ebonite  turn-buckle  over  the  jaw  for  increased 
safety  and  with  a  brass  pin  to  hold  the  knife  locked  in  the  jaws  when  desired. 

(B)    THE  ELECTRIC  FUSE. 

The  electric  fuse  offers  the  safest,  simplest,  cheapest  and  most  effective  means 
of  firing  high  explosives  or  large  charges  of  powder,  and  the  only  means  of 
igniting  separate  charges  simultaneously  for  greater  destructiveness 
or  a  single  charge  from  a  distant  point,  or  at  a  required  moment,  or 
under  water. 

I. — It  consists  of  about  ^-inch  length  of  fine  wire  of  platinum- 
iridium  alloy,  0.001  to  0.003  inch  diameter,  £  ohm  to  1  ohm  resistance 
cold,  called  the  bridge  which  is  surrounded  by  a  little  gun  cotton ; 
next  to  this  is  placed  fine  gunpowder  for  igniting  a  powder  charge 
or  mercuric  fulminate  for  detonating  high  explosives.  The  whole 
is  fixed  within  a  copper  case.  An  electric  current  of  specified 
strength  reddens  the  bridge,  ignites  the  gun  cotton  and  fires  the  fuse. 

1.  The  commercial  fuse  (fig.  143  is  actual  size)  has  a  copper  shell 


c- — 


A  with  corrugation  to  hold  more  firmly  the  sulphur  cement  F 
which  seals  up  the  open  end  and  holds  firmly  in  place  the  fuse  wires. 
B  is  the  chamber  containing  20  to  50  grains  of  fulminate.  A  little 
gun  cotton  surrounds  the  bridge  which  is  soldered  to  the  bared  ends 
of  the  fuse  wires  D.  The  wires,  4  to  40  feet  long, 
have  cotton  cover  soaked  in  asphalt  for  ordinary 
outdoor  work  and  gutta-percha  covering  for  sub- 
marine work. 

c         2.  The  United  States  Navy  electric  fuse  (fig. 

144)  has  the  copper  case  in  two  parts  which  screw 
together,  TVinch.  The  upper  or  inside  part  holds 
35  grains  of  the  fulminate.  The  lower,  open  at 
both  ends,  is  filled  with  sulphur  and  glass,  which 
holds  fixed  in  place  the  wire  ends  and  bridge. 
When  the  fulminate  is  dry,  the  spaces  in  both 
parts  are  filled  with  dry  pulverulent  gun  cotton 
and  the  parts  are  screwed  together. 

3.  The  mine  fuse  (fig.  145),  without  the  copper 
case  and  fulminate  may  be  used  in  ordinary  work 
to  fire  gunpowder.  To  detonate  explosives,  attach  the  cop- 
per case  containing  mercuric  fulminate  which  varies  in  quan- 
tity with  the  kind  and  size  of  the  charge. 

Plug  K  has  two  opposite  longitudinal  grooves  in  which  the 
lead  wires  C  C,  covered  with  paraffined  cotton  braid,  are 
buried.  A  cut  round  the  middle  allows  the  two  leads  to  cross 
half  over,  so  that  each  lead  leaves  the  plug  in  the  opposite 
groove  from  that  which  it  entered,  thus  holding  the  wires 
fast.  The  cap  B  fits  tightly  over  K  and  is  glued  to  it  in  a 
solid  piece.  The  copper  case  slips  over  the  whole  and  is  held 
by  dents  near  the  end. 

F,  gun  cotton;'  <?,  fui-  4.  The  gun  fuse  (fig.  146)  has  a  brass  case  a  threaded  on 
minate;  H,  fuse  wires,  the  exterior  to  screw  into  the  axial  vent  of  the  breechblock  to 
the  shoulder.  Its  rear  part  is  squared  for  a  wrench.  The  interior  is  thinned  at  b 
for  a  gas  check.  A  hard  rubber  plug,  /,  holding  in  a  fixed  position  the  leads  to 
the  bridge,  is  seated  at  c.  Small-arms  powder  surrounds  the  bridge  and  gun 

(109) 


143. 


-JT 


144. 

A,  lower  tube;  B,  up- 
per tube;  C,  plug  of  sul- 


110 


HANDBOOK    FOR   ELECTRICIANS. 


cotton.  The  escape  of  gas  outside  the  fuse  is  prevented  by  the  expansion  of  the 
thin  part  at  fr,  and  inside  the  fuse  by  the  hard  rubber  being  driven  into  the 
enlargement  of  the  wire  duct. 

II.  —  The  electrical  tests  of  a  fuse  are  for  — 

1.  Conductor  resistance  cold  (bridge  and  short  leads),  0.3  to 
1  ohin. 

2.  Conductor  resistance  hot  just  before  ignition,  0.45  to  2  ohms. 

3.  Insulation  resistance  between  conductor  and  case,  1  meg- 
ohm. 

4.  Strength  of  current  required  to  fire,  0.3  to  0.8  ampere. 
The  testing  current  ought  not  to  exceed  one-tenth  of  that 

necessary  to  fire. 

III.  —  Placing  the  fuse  in  a  mine  charge  — 

1.  If  of  gunpowder,  fill  the  bag  one-third  full,  put  the  fuse, 
or  two  fuses  in  parallel,  on  top,  fill  up  the  bag,  leaving  6  inches 
slack  in  the  wires,  and  lash  tightly  the  mouth  of  the  bag  and 
wires.     If  the  bag  is  vulcanized  india  rubber  for  service  under 
water,  the  mouth  is  well  smeared  with  india  rubber  solution 
and  closed  between  two  hard-wood  clamps  bolted  together. 
Tension  on  the  fuse  is  prevented  by  a  stout  string  from  the 
clamp  hitched  to  a  point  on  the  fuse  wires. 

2.  If  the  charge  is  gun  cotton,  insert  the  detonator  in  the 
hole  of  the  priming  disc  and  lash  the  wire  to  the  disc  which  is 
P^ced  centrally  in  the  charge.     If  the  latter  is  very  large,  two 

If 


145.  Mine  Fuse. 


A ,  copper  case ; 
hollow  wood  cap  ;  i 
wires,  0.035  inch ;  ^,  -  .  -  - 

bridge,  0.0025  inch ;  F,  OT  three  priming  discs,  each  with  its  detonator,  are  used, 
priming ;  H,  fulminate  the  charge  is  wet  gun  cotton  the  primer  must  be  dry  and 
grains1-0  j^pape/disct  encased  to  be  kept  dry. 
held  by  drop  of  coiio-     3.  In  a  dynamite  or  gelatine  cartridge  (147), punch  with  ahard- 

wood'. 


146. 


-  wood  pin  a  hole  in  the  lower  end  or  middle,  1  inch  longer  than 
the  detonator  and  without  removing  the  paper  cover.     Press 

the  cartridge  to  close  the 
mouth  of  the  hole  after 
insertion,   and  lash*  with 
string  the  wires  along  the 
cartridge.   Half  hitches  or 
other  tying  of  the  wires 
may  cause  short  circuits. 
IV.—  To  fire  with  a  battery.—  See  that  all  persons  are  distant  or  protected: 
attach  the  leads  ;  close  the  switch  firmly  ;  detach  the  leads. 

Before  using  the  battery  ascertain  from  its  constants  and  external  resistance 
if  it  can  supply  the  necessary  current  strength  to  each  fuse.  In  no  case  can  this 
be  less  than  the  current  given  for  ignition,  nor  be  more  than  25  per  cent  in 
excess.  If  the  fuses  are  two  in  parallel,  instead  of  all  being  in 
series,  double  the  current  will  be  required. 

V.  —  To  fire  ivith  the  service  dynamo.  —  1.  If  no  one  is  near 
the  mine  or  gun,  connect  the  leads  to  the  posts  ;  seize  the  handle 
with  one  hand;  steady  the  box  with  the  other;  lift  the  ratchet-bar 
to  its  full  length,  then  press  it  down  quickly  with  constant 
force  until  the  bar  strikes  the  bottom  with  a  thud,  when  the 
fuses  will  be  fired  ;  detach  the  wires.  Churning  the  bar  up  and 
down  to  fire  is  useless  and  harmful. 

When  there  are  three  binding  posts  on  the  box  (fig.  148)  and 
the  number  of  fuses  is  small,  join  the  leads  to  the  middle  and 
either  outside  post  ;  when  the  number  of  fuses  is  large,  join  the 
the  main  leads  to  the  outside  posts  and  run  a  third  lead  from 
the  middle  post  to  a  point  midway  of  the  fuses  in  series. 

2.  In  case  of  failure  to  fire  when  the  number  of  fuses  does  not 
exceed  the  capacity  of  the  battery  or  dynamo,  there  is  probably 

a  break,  a  poor  joint  or  a  contact  between  the  two  leads.    The  ,47 

leads  being  detached,  go  over  the  whole  circuit,  lifting  up  the 
wire  in  search  of  a  break  inside  the  insulation,  examining  the  joints  and  watch- 
ing for  contacts.     If  this  fails  to  reveal  the  open  circuit,  locate  it  by  use  of  a 
single  high  resistance  cell  and  the  fine  wire  coil  of  the  detector  or  other  Galv.  of 
sufficient  resistance  to  keep  the  testing  current  below  &  ampere. 

3.  If  trouble  is  suspected  in  the  dynamo,  try  a  fuse  through  a  resistance  ;  or,  if 
after  removing  the  endboards,  a  spark  is  seen  at  the  short-circuiting  key  wln-n 
the  bar  strikes  it.  the  dynamo  is  in  order.     The  resistance  between  the  two  bind- 
ing posts  should  be  zero  when  the  bar  is  up  and  about  6  ohms  when  pressed 


MISCELLANEOUS    APPARATUS. 


Ill 


down  hard.  When  there  are  three  posts  and  the  bar  is  up,  the  R  between  the 
left-hand  and  middle  ones,  looking  at  them  from  their  side  of  the  box  is  0,  and 
between  the  middle  and  right  ones,  infinity. 

VI. — Precautions  in  firing  fuses  are  as  follows: 

The  last  thing  done  around  a  mine  or  a  gun  is  the  joining 
of  the  fuse  wires  to  the  leads. 

At  the  battery  or  dynamo  just  before  firing,  attach  the 
leads  to  the  posts. 

Place  battery  or  dynamo  in  a  safe  place  and  as  near  the 
mine  as  safety  permits. 

A  rough  test  of  the  generator  just  before  firing  can  be 
made  by  its  bringing  for  an  instant  to  a  barely  perceptible 
red,  a  certain  length  of  platinum  fuse  wire ;  or  by  firing  a 
single  fuse  through  a  given  resistance. 

The  service  dynamo  will  fire  a  very  few  fuses  joined  two 
in  parallel. 

In  jointing,  scrape  clean  the  ends,  wind  closely,  solder 
if  convenient,  with  resin  for  the  fiux,  and  in  all  cases  wrap 
the  joint  with  tape. 

Fuses  must  be  kept  in  a  dry  place  remote  from  explosive 
or  strong  acid,  and  should  be  tested  before  using. 

Fuses  varying  1 0  per  cent  or  more  from  their  specified 
resistance  are  rejected. 

Put  detonators  under  test  in  a  safety  box ;  never  turn  a 
detonator  toward  a  person. 

A  detonator  must  on  no  account  be  bent,  struck,  heated 
or  roughly  handled. 

Avoid  strain  on  a  fuse  by  hitching  a  tension  string  from 
the  charge  case  to  the  fuse  wires. 

For  certainty  of  ignition  of  a  single  important  charge, 
two  fuses  are  connected  in  parallel. 

Always  use  fuses  of  the  same  kind  in  a  circuit.  Lead 
wires  have  double  the  diameter  of  fuse  wires. 

G-uard  against  injury  to  insulation  in  tamping,  and  bare 
wire  at  a  joint  or  other  point  in  the  circuit. 


148.  30=Fuse  Firing 
Dynamo, 


(C)  ELECTRIC  BELLS. 

1.  Electric  bells  are  of  two  kinds— single  stroke  (fig.  149)  and  vibrating. 
In  the  vibrating  bell  (fig.  150),  the  armature  is  held  by  a  spring,  C,  against  B, 
adjustable  at  D.     The  key  K  being  closed,  a  current  flows  through  L,  P,  B,  F,  C, 
E,  P,  K  and  L,  attracting  the  armature,  striking  the 
gong  and  breaking  the  circuit  at  B.     As  no  current 
now  flows,  the  spring  at  C  throws  the  armature  back 
against  B,  reestablishing  the  current  which  acts  as 
before.     Both  contact  points,  B  and  F,  are  of  platinum 
to  prevent  corrosion  by  the  spark. 

2.  Trouble  in  bell  circuits  is  usually  due  to  dirty 
contacts  at  B  and  F,  or  to  some  part  of  the  circuit 
touching  the  metal  frame  or  to  a  break  in  the  circuit, 
usually  at  a 
binding 
post,  key  or 
joint.  Use 
insulated 
149.  ISO.  wire  only;  m  152 

fasten  wires 

under  composition  staples  without  bending  the  wire ;  keep  parallel  wires  one- 
half  inch  apart ;  never  run  two  wires  under  the  same  staple  or  through  the  same 
hole ;  solder  splices,  and  cover  with  insulation. 

To  ring  two  or  more  bells,  each  with  its  own  button,  by  means  of  one  battery, 
see  fig.  151. 

To  ring  one  bell  with  one  battery  from  two  or  more  buttons,  see  fig.  152. 


112 


HANDBOOK   FOR    ELECTRICIANS. 


(D)  THE  ANEMOMETER  (FIG.   153). 

The  anemometer  measures  the  velocity  of  the  wind  in  miles  per  hour. 

1.  It  should  be  placed  on  top  of  a  telegraph  pole  or  other  support  without 
vibration,  erected  on  the  highest  site  in  the  vicinity.     Any  obstruction  within 
500  feet  of  the  site  and  10°  or  more  above  it  is  objectionable,  as  the  velocity  of 
the  wind  is  diminished  by  friction  from  20  to  50  per  cent  within  100  feet  above 
the  ground.     Two  wires  run  from  it  to  the  distant  register. 

2.  Four  brass  cups,  C,  on  the  ends  of  arms,  in  a  wind,  turn  a  vertical  shaft, 
A,  whose  screw  thread,  B,  is  geared  into  wheel,  D.     Two  D-shaped  lugs  on  the 
wheel  are  arranged  as  shown  to  close  momentarily  an  electric  circuit  every  25 
revolutions  on  a  single-stroke  bell,  every  500  revolutions  on  a  self -register,  and 
permanently  during  25  revolutions  on  the  stop  clock.     The  wheel  must  be  spe- 
cially constructed  for  each  of  the  above  registers ;  for  the  stop  clock  the  two 

D-lugs  are  replaced  by  a  semicircular  ridge  join- 
ing their  positions,  which  then  closes  the  circuit 
during  one -half  revolution  of  the  wheel. 

3.  To  get  roughly  the  velocity  of  the  wind  in 
miles  per  hour  with  the  single-stroke  bell,  connect 
up  anemometer,  bell,  and  battery,  as  in  fig.  153. 
Note  by  means  of  the  secondhand  of  an  ordinary 
watch  the  number  of  seconds  between  two  con- 
secutive strokes.     Divide  180  by  that  number. 

EXAMPLE. — The  seconds  hand  stood  at  32  when 
the  anemometer  rung  the  bell  and  at  47  at  the 
next  stroke.  Required,  the  velocity.  Interval  — 
15  seconds;  180  -T-  15  =  12  miles  an  hour,  approx- 
imate. 

4.  Anderson's  stop  clock  performs  the  above 
automatically  and  more  accurately,  its  electro- 
magnet taking  the  place  of  the  bell's  magnet  in 
fig.  153.    Its  single  second's  hand  moves  over  a  dial 

AM  rij  having  two  scales — the  inner  one  representing  in 
liL  &  *" T  **ie  usual  wav  seconds  to  a  total  of  60,  the  other 

scale  of  unequal  parts,  velocities  in  miles  per  hour. 
Experience  shows  that  the  velocities  are  a  little 

,  r „  .  |  .    |    greater  than  those  given  by  the  above  rule. 

Tf      ~w  iTy        By  means  of  a  lever  and  cam,  the  seconds  hand 

I j~T     can  be  brought  to  the  vertical  or  0  position  from 

' '     any  other  on  the  dial.     A  very  light  spring  on  the 

153.  Anemometer.  movable  end  of  the  armature  bears   normally 

against  the  balance  wheel  and  thus  keeps  the  clock  from  running ;  when  the 
magnet  is  energized  from  the  anemometer,  the  armature  both  releases  and  starts 
the  balance  wheel,  and  the  clock  runs  while  the  cups  make  25  revolutions,  or 
the  air,  ^  mile ;  the  armature  then  released  stops  the  clock. 

To  operate:  Close  the  circuit;  bring  the  hand  to  0;  if  it  then  starts,  the 
anemometer  has  closed  the  circuit  and  it  will  be  necessary  to  wait  until  the  hand 
stops,  when  reset  it  at  0.  In  a  few  moments  it  will  automatically  start  and  later 
stop  and  register. 

5.  Gibbon's  self -register  (fig.  154)  has  an  electro-magnet  in  the  place  of  the 
bell's  magnet  of  fig.  153,  and  a  4-inch  diameter  drum  revolved  uniformly  and 
translated  longitudinally  by  clockwork  so  that  the  point  of  a  fixed  pencil  will 
describe  a  spiral  upon  a  sheet  of  paper  laid  upon  the  drum's  surface.  The 
pencil  is  held  at  the  movable  end  of  the  magnet's  armature.  The  paper  is  ruled 
parallel  with  the  drum's  axis  into  five  minute  spaces. 

Whenever  the  anemometer,  after  the  connections  are  complete,  makes  about 
500  revolutions,  corresponding  to  points  moving  with  the  wind  exactly  1  mile 
apart,  it  closes  the  circuit  and  the  pencil  makes  a  sharp  dent  in  the  spiral. 

To  put  the  sheet  on  the  drum,  place  the  cylinder  S  on  a  table  with  the  screw 
T  to  the  left-hand ;  place  the  paper  on  the  cylinder  with  the  top  of  it  from  the 
screw.  Let  the  line  marked  12  noon  come  on  the  line  of  the  cylinder,  and  place 
a  rubber  band  on  each  end.  The  lines  at  each  end  of  the  paper  will  then  exactly 
coincide.  Place  the  cylinder  S  in  its  position,  so  that  the  end  opposite  to  the 
screw  T  will  be  near  the  post  on  which  it  rests.  Slide  the  small  sliding  bar  on 
the  horizontal  bars  O  O  until  it  fits  on  the  ends  of  the  screw-axle  T;  then 
revolve  the  cylinder  until  the  pencil  rests  on  the  end  of  the  upper  line  marked 
12  noon,  or  the  line  corresponding  to  the  hour  at  which  the  instrument  is  set, 
and  tighten  the  thumbscrew  N. 


MISCELLANEOUS   APPARATUS. 


113 


To  obtain  the  velocity  from  the  self -register  take  the  number  of  spaces  and 
parts  of  spaces  between  the  mile  marks  recorded  in  the  five  minutes  preceding 
the  time  of  observation  and  multiply  the  result  by  twelve. 


TO  ANEMOMETER, ' 


FROM  ANEMOMETER. 


154. 


Ex:  Suppose  the  number  of  spaces  indicating  mile  marks  between  8.55  and 
9  a.  m.  were  1£;  then  the  velocity  of  the  wind  is  1£  X  12  =  15  miles  per  hour. 
When  the  velocity  is  less  than  twelve  miles  per  hour  the  velocity  will  be 
determined  as  follows :  If  the  interval  between  the  last  two  mile  marks  is  7 
minutes,  then  the  current  hourly  velocity  will  be  obtained  by  dividing  60  by 
7  =  8|  miles. 

6.  The  velocity  of  the  wind  may  be  roughly  'estimated  without  anemometer : 


Name. 

Miles 

per  Hour. 

Apparent  Effect. 

Calm.  . 

o 

No  visible  horizontal  motion  to  inanimate  matter 

Light      _ 

1  to     2 

Causes  smoke  to  move  from  the  vertical 

Gentle 

3  to     5 

Fresh    _ 

6  to  14 

Moves  small  branches  of  trees  and  blows  up  dust 

Brisk 

if.  to  24 

High 

25  to  29 

Kiilf 

40  to  59     _ 

Dangerous  for  sailing  vessels 

Storm 

60  to  79 

Hurricane  

80  or  more  

Prostrates  everything. 

To  find  the  pressure  of  the  wind  in  pounds  upon  a  surface  exposed  perpen- 
dicularly to  the  wind,  multiply  together,  0.005,  the  surface  in  square  feet,  and 
the  square  of  the  velocity  of  the  wind  in  miles  per  hour.  Or,  P  =  0.005  SVS. 

7.  Care  of  Anemometer. — Keep  mechanism  clean  and  bearing  parts  oiled  with 
clock  oil.  The  anemometer  should  be  compared  every  season  and  found  to 
agree  with  at  least  two  others  supposed  to  be  in  good  order. 


XII.— PRIMARY  BATTERIES. 


(A)    GENERAL   DIRECTIONS. 

1.  When  any  two  different  metals  are  partially  immersed  without  touching 
in  a  liquid  which  acts  more  upon  one  than  the  other,  the  combination  forms  an 
electric  cell;  if  a  wire  joins  the  metals  outside  the  liquid,  a  current  of  electricity 
will  flow  around  the  circuit  thus  formed.     Zinc  is  usually  one  of  the  metals  or 
plates  ;  copper  or  carbon  is  the  other  and  its  upper  part  is  the  positive  pole  of  the 
cell.     Sometimes  two  liquids  are  used  —  each  around  its  own  plate  —  and  kept 
separate  by  a  porous  diaphragm  or  by  gravity. 

2.  The  current  from  an  electric  cell  diminishes  after  a  time  more  or  less  rapidly, 
due  chiefly  to  three  causes  :  (  1  )  impurities  in  commercial  zinc,  causing  local 
action  ;  (2)  the  production  of  new  and  hurtful  compounds  in  the  cell  ;  and  (3)  polar- 
ization, or  the  formation  on  the  copper  or  negative  surface  of  hydrogen  gas  which 
not  only  increases  the  resistance  of  the  cell  but  tends  to  make"  the  poles  alike. 

(1)  Local  action  is  remedied  by  coating  the  zinc  surface  with 
mercm>y>  a  process  called  amalgamation  ;  (2)  hurtful  compounds 
are  removed  from  time  to  time;  (3)  polarization  is  partially  or 
wholly  checked  by  enlarging  and  roughening  the  surface  of  the 
negative  plate,  or,  preferably,  by  surrounding  it  with  an  oxide  or 
other  substance,  termed  a  depolarizer,  which  takes  up  the  hydro- 
gen as  it  forms. 

3.  Management.  —  (a)  In  mounting,  see  that  all  the  parts  are 
clean,  the  bearing  surfaces  of  connections  brightened  and  the 
connections  made  tight  by  using  English  binding  posts,  or  doub- 
ling the  wire  through  holes  too  large,  so  as  to  fit.  Use  only  rain 
water  and  the  best  materials.  Do  not  spill  liquid  or  salt  over 
parts  to  remain  dry.  The  two  plates  of  a  cell  should  not  touch, 
Cells  of  different  kinds  are  never  joined  in  the 


(  ___ 


^  ojf 


155.  Typical. 

nor  any  two  cells  of  a  battery, 
same  battery. 

(6)  For  proper  maintenance  all  cells  should  have  covers  to  prevent  evapora- 
tion, all  zincs  in  acids  should  be  amalgamated  to  prevent  local  action,  and  rims 
of  jars  should  be  dipped  about  an  inch  in  melted  paraffine  to  prevent  salts  from 
creeping  over.  Keep  cells  well  insulated  on  porcelain  holders  or  paraffined  wood 
in  a  dry,  cool  and  clean  place,  especially  free  from  dust  and  change  of  tempera- 
ture. The  cells  are  preferably  arranged  in  single  rows  on  shelves  accessible 
on  both  sides  and  having  a  hood  to  carry  off  the  gases.  Direct  sunlight  on 
glass  jars  may  crack  them. 

The  battery  room,  dry,  light,  ventilated,  and  with  cement  floor,  should  have  a 
sink  with  entrance  and  exit  water  pipes,  and  such  facilities  as  spare  jars,  pitcher, 
scales,  brushes,  syringe,  hydrometer,  funnels,  graduated  glass  and  mercury 
dish.  All  trace  of  grease  or  soap  must  be  excluded. 

(c)  After  dismounting,  all  battery  parts  are  cleaned  while  wet.  Scrape  off  old 
salt  and  crust,  and  rub  with  a  brush  until  a  bright  surface  appears.  If  plates 
are  greasy,  soak  in  strong  soda  solution.  Carbon  plates  and  porous  cups  are 
soaked  in  water  several  hours.  Re-amalgamate  the  zincs.  File  or  rub  with 
emery  the  connections,  and  finally  dry,  reparaffine  and  repaint  with  asphaltuin. 
Varnish  the  tops  of  plates. 

4.  Amalgamating  zincs.— First  clean  the  zincs,  then  dip  in  sulphuric  acid 
solution  (-fo),  or  any  old  acid  solution,  about  one  minute.     Then  transfer  it  to  an 
open  shallow  dish  of  iron  or  porcelain  whose  bottom  is  covered  with  mercury 
and  a  little  of  the  solution.     While  turning  the  zinc  over  so  that  every  part 
comes  into  the  mercury,  rub  the  surface  with  a  swab  made  by  winding  cloth 
around  the  end  of  a  stick. 

Or,  mix,  by  weight,  1  part  nitric  and  2  parts  hydrochloric  (muriatic)  acid  and 
add  slowly  \  part  mercury.  When  dissolved  add  3  parts  more  of  hydrochloric 
acid  and  stir.  Clean  the  zinc  with  potash  and  water ;  immerse  in  the  above 
solution  for  a  few  seconds.  Rinse  in  clear  water  and  rub  with  battery  brush. 

5.  Solutions  are  mixed  in  large  jars  to  obtain  uniformity  by  pouring  in  first 
rain  or  pure  water,  and  adding  the  acid  slowly  while  stirring.     Let  the  mixture 
cool  and  settle  and  do  not  use  the  sediment. 

(114) 


PRIMARY   BATTERIES. 


115 


156.  Sampson. 


6.  The  desirable  qualities  of  a  cell  are  (1)  a  large  and  constant  E,  (2)  a  small 
and  constant  R,  (3)  cheapness  of  materials,  (4)  no  waste  of  materials  when  not 
giving  a  current,   (5)  easily  inspected,   (6)   easily  refreshed,   (7)  no  offensive 
fumes,  (8)  first  cost  small.     No  one  cell  has  all  of  them. 

7.  Several  cells  of  the  same  kind  and  size  may  be  united  in  series,  parallel  or 
both,    to  form  a  battery.      The  two  forms  of  battery  are  the  primary  and 
secondary.     There  are  five  different  kinds  of  primary  in  general  use — Leclanche, 
dry,  gravity,  copper  oxide,  and  bichromate. 

(B)  SPECIAL  DIRECTIONS. 

(a)  LECLANCHE  CELL  (Fia.  156) 

1.  A  zinc  rod,  or  cylinder,  and  a  carbon  cup  containing  a  mixture  of  nearly 
equal  amounts  of  broken  carbon  and  manganese  bioxide  stand  in  a  saturated 
solution    of    sal  ammoniac.     E  =  about  1.48  volts;   R  of  5 

by  7  inch  cell  with  zinc  rod  is  about  1  ohm. 

2.  The  Leclanche  furnishes  a  strong  current  for  a  short 
time,  but  it  soon  begins  to  polarize.     Left  on  an  open  circuit, 
it  regains  its  strength  without  the  consumption  of  material. 
It  is  useful  for  intermittent  work  only. 

3.  Mounting. — Fill  the  jar  about  one-third  full  of  water  and 
stir  in  about  4  ounces  of  sal  ammoniac,  so  that  there  may  not 
remain  an  excess  of  the  white  salt.     Put  in  the  two  plates 
with  cover.     Liquid  is  about  2  inches   from   the  top.     If 
porous  cup,  let  the  cell  stand  twelve  hours  before  using ;  or 
better,  fill  the  cup  with  solution  through  the  gas  hole  in  the 
seal.     If  prisms,  they  are  held  tight  against  the  carbon  by 
two  strong  rubber  bands. 

4.  Maintenance. — Add  water  as  it  evaporates  and  a  little 
salt  as  the  current  gets  weak.     Wipe  off  the  first  trace  of 

white  salt  forming  on  the  tops  of  parts  due  to  carelessness  in  setting  up  the 
cell.     Hard  scale  on  plates  shows  that  the  solution  is  too  strong. 

Never  leave  the  cell  on  closed  circuit  and  for  safety  detach  both  poles  when 
the  cell  is  not  required.  If  a  Leclanche  fails,  examine  the  connections,  or  add 
a  little  salt,  or  replace  the  solution  with  new,  or  soak  carbons  in  hot  water  for 
three  hours,  or  scrape  off  the  hard  scale,  or  fill  carbon  cup  with  fresh  mixture, 
or  throw  away  all  except  the  jar. 

A  green  salt  forming  on  a  binding  post  is  cleaned  and  the  metal  part  is  recoated 
with  asphalt.  One  carbon  outlasts  three  zincs;  one  zinc  rod  gives  30  to  40 
ampere  hours. 

(b)  THE  DRY  CELL  (Fio.  157) 

Belongs  to  the  Leclanche  class.     A  zinc  can  enveloped  in  pasteboard,  and 
always  having  a  sealed  cover,  serves  both  as  jar  and  plate. 

1.  The  central  cylinder  of  carbon  and  manganese  oxide 
is  surrounded  by  an  absorbent  or  gelatinous  body  well  soaked 
in  an  exciting  solution  of  1  part  (by  weight)  sal  ammoniac, 
1   part  Zn.    chloride,  3  parts  plaster,  2  parts  water.     The 
ingredients  are  often  kept  secret. 

2.  E=\A  volts,  and  R  =  about  1  ohm  for  a  5-inch  cell. 
Its  ampere  hours  is  less  than  for  a  liquid  Leclanche.     But 
it  is  cheap,  portable,  may  be  laid  in  any  position,  and  kept 
for  a  long  time  if  not  overworked  and  if  the  inside  moisture 
does  not  escape.     A  good  dry  cell  may  ring  a  door  call  bell 
eighteen  months. 

3.  If  it  fails,   bore  a  small  hole  in  the  seal  and  inject 
water.     If  its  strength  is  regained,  seal  up  the  hole  tightly; 

|hl  otherwise  throw  the  cell  away. 

(c)  GRAVITY  CELL  (FiG.  158). 

1.  A  zinc  plate,  Z,  stands  in  a  solution  of  zinc  sulphate, 
and  a  copper  plate,  C,   in  a  solution   of  copper  sulphate 
(bluestone) ,  the  copper  being  at  the  bottom.    E  =  about  1.08 
157.  Dry  Cell.        volts.     R  of  a  6  by  8  inch  cell  in  good  condition  is  about  3 
ohms.     The  gravity  gives  a  steady  current  in  a  closed  cir- 
cuit and  is  employed  for  continuous  work  only.     Good  forms  are  Crowfoot 
and  Eagle. 


116 


HANDBOOK    FOR   ELECTRICIANS. 


2.  Mounting. — Unfold  the  leaves  of  the  crowfoot  copper  so  as  to  form  a  cross, 
place  it  in  the  bottom,  bring  its  wire  tip  straight  and  bend  it  sharply  over  the 
edge  for  a  clamp.  Drop  in  crystals  of  copper  sulphate,  about  three  pounds,  to 
the  top  of  the  leaves.  Pour  in  rain  or  soft  water  until  it  covers  the  zinc,  put  on 
the  cover  and  short-circuit  for  two  or  three  days.  If 
wanted  sooner,  let  the  water  come  to  within  an  inch  of  the 
zinc  and  then  pour  carefully  on  top  a  solution  of  3  ounces 
of  zinc  sulphate  in  sufficient  water  to  cover  the  zinc,  or 
zinc  solution  from,  an  old  jar,  if  clear,  or  a  little  sulphuric 
acid. 

3.  Maintenance. — The  cell  is  in  good  condition  when  the 
lower  copper  solution  has  a  deep  blue  color  up  to  the  point 
midway  between  the  plates  and  the  upper  zinc  solution,  of 
1.1  specific  gravity,  is  clear  like  water,  and  when  the  divid- 
ing line  between  them  is  sharp.  If  the  blue  rises  higher, 
reduce  the  external  resistance  or  short-circuit ;  if  it  sinks 
much  below  the  middle,  leave  it  on  open  circuit  a  few 
hours.  The  cell  normally  should  remain  closed  on  a  resist- 
ance and  never  jarred  nor  the  plates  within  be  disturbed. 
Copper  sulphate  crystals  should  always  be  seen  in  the  bot- 
158.  Gravity,  Crowfoot  *om-  When  the  zinc  solution  becomes  too  heavy,  causing 
salt  to  form  on  the  upper  parts  and  copper  on  the  zinc,  or 

the  specific  gravity  reaches  1.2,  remove  the  top  liquid  by  means  of  a  syringe  to  an 
inch  below  the  zinc,  and  replace  with  water  slowly,  so  as  not  to  disturb  the 
solution  below.  When  metallic  copper  forms  on  the  zinc,  take  out  the  plate, 
scrape  off  the  mud,  chip  off  any  cake  formation,  and  after  dropping  in  large 
crystals  of  bluestone  (if  needed),  replace  the  zinc  and  cover. 

4  Dismounting. — Take  out  the  plates  and  save  the  top  clear  liquid  to  start  the 
new  cells.  With  a  hammer  and  knife  remove  the  hard  crust  from  the  zinc  and 
the  deposit  from  the  copper.  See  that  the  attached  wire 
is  firmly  riveted  to  the  copper  plate  and  that  there  is  no 
break  in  the  insulation. 

5.  The  Eagle  cell  is  for  portability.  — Fill  the  lead  jar  ( fig. 
159),  whose  inner  surf  ace  has  been  brightened,  one-third  or 
one-fourth  full  of  copper  sulphate  and  cover  with  two- 
inch  thickness  of  pressed  excelsior,  sponge  or  sawdust  on 
which  rests  the  zinc.  Wooden  sticks  suspended  from  the 
rim  prevent  the  zinc  from  touching  the  jar.  Pour  in 
water  until  it  covers  the  zinc  and  short-circuit  for  three 
or  four  days.  Let  the  jar  stand  on  wood  soaked  in 
paraffine  or  on  glass. 

(d)  COPPER  OXIDE  CELL  (Fia.  160). 

159.  Eagle. 

1.  Plates  of  zinc  and  of  copper  oxide  stand  in  a  one- 
fourth  solution  by  weight  of  caustic  potash.     E  =  about  0.8  volt.     R  of  the 
5  by  8  inch  cell  with  oxide  between  two  zinc  plates  is 
about  0.07  ohm.     The  cell  is  for  either  continuous  or  inter- 
mittent work. 

2.  Mounting. — Place  the  potash  in  the  jar,  and  pour  in 
water  until  its  level  shall  be  ±  inch  above  the  oxide  plates 
when  in  position.     Stir  with  a  stick  at  intervals  so  as  not 
to  cause  too  great  rise  of  temperature  until  the  salt  is  dis- 
solved.    Pour  carefully  on  top  heavy  paraffine  oil  so  as  to 
form  a  layer  £  inch  thick. 

Pass  the  ends  of  zincs,  well  amalgamated,  through  the 
middle  hole  of  porcelain  cover  and  fasten  them.  Put  the 
copper  oxide  plates  in  their  frames,  slip  on  the  hard  rub- 
ber separators,  pass  the  ends  of  the  frames  through  the 
holes  in  the  cover  and  fasten  them.  Put  plates  and  cover 
in  position.  If  a  strong  current  is  wanted  at  once,  short- 
circuit  for  ten  or  fifteen  minutes. 

3.  Maintenance. — If  necessary,    move  the  cell  without 
shaking.     Glass  jars  are  liable  to  crack.     The  top  layer  of 

oil  is  very  essential  and  the  level  of  the  dividing  line  previously  marked  on  the 
jar  inside  should  be  well  above  the  oxide  plates.  There  is  no  local  action  on 
open  circuit.  All  materials  are  proportioned  to  be  consumed  in  practically  the 
same  time. 


160.  Copper  Oxide. 


PRIMARY   BATTERIES. 


117 


(e)  BICHROMATE  CELL  (FiG.  161). 

1.  Zinc  and  carbon  plates  stand  in  a  solution  of  sulphuric  acid  and  bichromate 
of  potassium  or  sodium.     E  =  2. 1  volts.     E  of  6  by  8  inch  cell  with  zinc  between 
two  carbons  =  about  0.08  ohm. 

The  Grenet  zincs  are  submerged  only  when  a  current  is  required. 
The  current  is  very  strong  for  a  few  hours. 

2.  Mounting. — To  1  gallon  of  water  in  an  earthen  vessel  add  from 
1  to  2  pints  of  sulphuric  acid,  according  to  the  strength  required. 
While  the  mixture  is  still  hot  stir  in  one  pound  of  bichromate  of  pot- 
ash pulverized.     When  cool  it  is  ready  for  use  and  is  known  as  elec- 
tropoion  fluid. 

3.  Maintenance. — Special  care  is  taken  to  keep  zincs  well  amalga- 
mated; they  should,  when  submerged,  reach  to  the  bottom  of  the 

jar  so  as  to  touch  a  little  mercury.  The  zincs  are 
raised  out  of  the  solution  when  not  in  use ;  the  carbons 
may  remain  or  not.  Draw  off  some  of  the  old  liquid 
when  it  changes  color  and  add  fresh. 

4.  The  Fuller  bichromate  (fig.  162)  is  used  with  long-dis- 
tance telephones.  Pour  an  ounce  of  mercury  into  the  porous 
cup,  3  by  7  inches,  put  in  the  zinc,  fill  the  cup  with  water 
and  stand  the  cup  with  its  contents  in  the  jar  containing,  by 
weight,  6  parts  sodium  bichromate,  17  sulphuric  acid,  and  56 
water.  Alongside  put  in  the  carbon  with  its  cover. 

The  zinc  remains  continuously  in  the  cell,  which  needs  no  atten- 
tion for  four  or  five  months  if  not  overworked ;  otherwise  once 
162  Fuller       a  month.     There  is  very  little  local  action  on  open  circuit.    When 
the  rich  orange  color  becomes  bluish,  add  crystals.     If  the  color 

is  still  orange  and  the  cell  weak,  add  acid.     If  the  cell  is  still  not  active,  renew 

the  whole  solution. 


XIII.— TELEGRAPHY. 


(A)  DIAGRAM  OF  MORSE  RELAY  TELEGRAPH  FOR      . 
LONG  LINES  (FIG.  163). 

The  main  circuit  is  drawn  full ;  the  local  circuits,  broken.  The  former  uses 
the  ground ;  the  local  circuits  are  metallic.  The  main  battery  of  gravity  cells 
in  series  may  be  at  any  point  of  the  main  circuit,  but  a  half  is  usually  located 
at  each  end ;  if  one  of  the  halves  has  copper  to  line,  the  other  must  have  zinc. 


165.  Diagram  of  Morse  Relay  Telegraph  for  Long  Lines. 

All  relays  of  the  same  circuit  should  be  alike.  Many  operators  read  the  relay 
and  dispense  with  the  local  circuit.  For  5-mile  circuits,  20-ohm  sounders  may 
take  the  place  of  relays  and  local  circuits ;  both  key  and  sounder  have  a  com- 
mon wooden  base  and  the  thin  brass  base  of  the  sounder  is  raised  -J-  inch  for 
greater  clearness. 

A  150-ohm  relay  has  about  4,320  turns  in  30  layers,  No.  30  on  each  core. 

A  4-ohm  sounder  has  about  470  turns  in  10  layers,  No.  24  on  each  core. 

A  20-ohm  sounder  has  about  938  turns  in  14  layers,  No.  25  on  each  core. 

It  is  plain  from  the  above  diagram  that  all  relays  and  sounders  will  respond 
to  any  key  in  the  circuit  and  to  one  key  only  at  a  time  if 
its  switch  is  open.     If  a  record  is  desired,  a  self -starting 
tape  register  takes  the  place  of  the  sounder. 


(B)  TELEGRAPH  CODE. 

The  dot,  dash  and  space  are  the  three  Morse  signals, 
and  different  combinations  of  them  form  the  letters. 

The  dot  (E)  is  made  by  a  momentary  downward  stroke 
of  the  key  lever.  This  is  the  unit  of  time.  The  dash  (T) 
is  made  by  holding  the  key  down  as  long  as  it  takes  to 
make  3  dots.  A  space  as  in  A  occupies  the  time  of  1  dot ; 
a  double  space,  as  in  R,  equals  2  dots. 

The  space  between  letters  is  equal  to  3  dots;  between 
words,  6  dots ;  the  sentence  space  is  filled  in  by  a  period. 

(118) 


164. 


TELEGRAPHY. 


119 


THE  MORSE  CODE. 


;  si 

:    KO 


!    __ 
»"QN 

H  - 

*8  SX 


ABBREVIATIONS. 


1  Wait  a  moment. 

4  Start  me. 

5  Have  you  anything? 

7  Are  you  ready  ? 

8  Busy  on  other  wire. 

9  Important,  give  way. 
13  Do  you  understand  ? 
18  What's  the  matter? 
30  Close  station. 

44  Answer  quickly. 
92  Delivered. 
134  Who  is  at  the  key? 


Ahr 

Ana 

Ck 

Col 

D 

Fm 

DH 

G  A 

GB 

GM 

GN 

GR 


Another. 
Answer. 
Check. 
Collect. 
Degrees. 
From. 
Deadhead. 
Go  ahead. 
Good  bye. 
Good  morning. 
Good  night. 
Gov't  rate. 


Msk 
NM 
OB 
OK 
Opr 
Pd 


Mistake. 

No  more. 

Official  business. 

All  right. 

Operator. 

Paid. 

Quick. 

Repeat,  are. 

Station. 

Signature. 

You. 

Ready. 


(C)  FORMS  OF  MESSAGE. 


Between  operators  whose  calls  are  S  and  J : 

Smith.  —  "Come  down  on  twelve  o'clock  train  if  you  are  off  duty." 
Jones. — "Shall  take  six  p.  m.  train." 

The  call,  message,  and  acknowledgment  in  which  Jones  fails  at  first  to  receive 
the  word  "twelve,"  and  missends  the  word  "take,"  occur  thus: 

Smith.— J  JJJSJJJSJ 

Jones. — III  J 


Smith. — II  Come  down  on  twel 

Jones. — G  A  on. 

Smith. — On  twelve  o'clock  train  if  u  r  off  duty 

Jones. — O  K  Shall  taken  _   _  _  __   _   take  six  p  m  train  J 

Smith.— O  K  S 

Regular  commercial  or  military  message: 

FORT  MONROE,  VA.,  July  30,  1901. 
JOHN  B.  THOMAS,  80  State  street,  Richmond,  Va. 
When  will  you  reach  Old  Point?    Telegraph  collect.     W.  J.  BODELL. 

It  would  be  telegraphed  as  follows : 

No  45  F  S  7  Paid  Fort  Monroe  Va  30  to  John  B  Thomas  80  State  street,  Rich- 
mond Va.  When  will  you  reach  Old  Point.  Telegraph  collect  Sig  W  J  Bodell. 

"No  45  F "  indicates  that  this  is  the  forty-fifth  message  sent  from  Fort  Mon- 
roe whose  office  call  is  F.  "S"  is  the  sending  operator's  personal  call, 
indicates  the  number  of  words  in  the  body  of  the  message  to  follow.  "Paid " 
indicates  that  the  message  has  been  paid  for ;  otherwise  the  word  is  "collect "  or 
"D  H"  (deadhead).  The  year  and  month  are  omitted.  A  period  immediately 
precedes  the  body  of  a  message  and  "Sig"  always  follows  it.  The  receiving- 
operator  whose  call  is  "A"  sees  that  the  message  is  apparently  correct,  verifies 
the  number  of  words  and  telegraphs,  "OKA." 

(D)  ADJUSTMENTS  OF  INSTRUMENTS. 

1.  Key.—  Loosen  the  binding  nuts  and  turn  the  trunnion  screws  close  up  so 
that  the  platinum  contact  points  will  touch  squarely,  then  turn  each  slightly 
back  so  that  the  key  lever  moves  freely  up  and  down  without  lateral  movement. 
If  necessary  rub  the  contact  points  with  fine  emery  occasionally  to  prevent 


120 


HANDBOOK   FOR   ELECTRICIANS. 


"sticking."  The  vertical  screws  of  the  key  should  allow  a  small  movement  of 
the  key  lever  with  a  moderate  spring  pressure.  See  that  all  the  binding  screws 
are  tight  and  that  the  switch  is  firmly  pivoted  by  its  screw  and  scrapes  well 
into  its  position  when  closed. 

2.  Relay  (or  sounder}. — The  trunnion  screws,  as  in  the  key,  should  allow  free 
motion  to  and  fro  (or  up  and  down)  without  lateral  movement.  Next  adjust 
the  front  (or  lower)  contact  screw  that  the  armature  may  not  strike  the  magnet 
cores  or  approach  nearer  than  the  thickness  of  writing  paper ;  withdraw  it  even 
further  if  the  armature  "sticks."  The  back  (or  upper)  binding  contact  screw 
should  allow  small  play,  but  sufficient  to  give  a  distinct  sound.  Adjust  the 
screw  of  the  spiral  spring  until  the  relay  (or  sounder)  strikes  with  the  key. 
Finally  see  that  all  of  the  binding  screws  are  tight. 

(E)   INSTRUCTIONS  FOR  OPERATORS. 

1.  Keep  key  closed  except  when  sending.     If  no  current  is  on  make  sure  that 
the  trouble  is  not  in  your  station ;  for  this  purpose  touch  a  short  piece  of  copper 
wire  across  the  main  wires  entering  the  station  to  observe  a  spark  or  taste  with 
the  tongue.     If  a  spark  is  seen  or  a  current  is  tasted,  the  trouble  is  probably  in 
your  station. 

2.  Keep  instruments  screwed  to  the  table  and  constantly  in  adjustment  so  that 
relay,  sounder  and  key  strike  together ;  that  all  binding  posts  and  screws  are 
tight;  that  the  ends  of  wires  entering  posts  project  through  them  and  are  bent 
around;  that  no  dust,  books,  papers,  etc.,  accumulate  on  or  about  the  instru- 
ments    The  table  should  be  screwed  down,  and  large  enough  to  rest  the  elbow 
in  sending.     Never  put  instruments  on  a  window  sill  or  expose  them  to  the 
weather. 

3.  To  prevent  instrument  from  working  when  not  required,  shunt  it  out. 
Never  screw  down  the  armature  lever  nor  alter  the  spring  nor  detach  the  wires. 

4.  To  call  a  station,  first  adjust  to  make  sure  the  line  is  not  in  use ;  if  not,  open 
the  key,  make  the  call  three  or  four  times  and  sign  your  own  call.     Repeat  until 
answered,  when  close  the  key. 

5.  To  answer  a  call,  wait  until  you  hear  the  signature,  then  open  the  key  and 
as  soon  as  the  distant  key  is  closed  repeat  the  letter  "I "  two  or  three  times,  or 
"OK"  once,  signing  your  own  call.     Close  the  key. 

6.  To  send  a  message,  call  the  station  as  above.     When  it  is  answered,  open 
the  key,  send  the  message  and  close  the  key.     If  a  mistake  occurs  make  inter- 
rogation or  six  dots  and  begin  with  the  last  word  sent  correctly.     Invariably 
observe  the  "forms"  of  message  above.     If  no  "O  K"  is  received,  the  call, 
answer,  and  message  are  repeated. 

7.  To  receive  a  message,  answer  the  call  and  prepare  to  write  down  the  mes- 
sage.    The  instant  a  word  is  missed,  break  and  telegraph  "G  A"  (go  ahead)  and 
the  last  word  received.     But  if  all  that  precedes  is  desired,  telegraph  "R  R." 
In  a  regular  message  verify  the  number  of  words  in  the  body  before  sending 
"O  K."    If  the  check  does  not  verify,  the  sender  must  give  the  initial  letter  of 
each  word  until  the  mistake  is  found. 

8.  In  the  body  of  a  message  abbreviations  do  not  occur,  numbers  are  spelled 
out,  periods  occur  between  sentences  but  not  at  the  end,  and  compound  words 
and  names  of  places  count  for  one  word. 

9.  Care  should  be  taken  to  send  uniformly.     It  is  more  difficult  to  send  well 
than  to  receive  well.     Few  operators  send  and  receive  40  words  per  minute ;  30 
words  is  very  rapid ;  the  average  speed  does  not  exceed  20.     Five  letters  count 
for  the  length  of  one  word. 

(F)   DIRECTIONS  FOR  BEGINNERS. 

1.  (1)  Memorize  the  alphabet.     (2)  Learn  with  the  aid  of  an  instructor  to 
write  Morse  with  the  key.     (3)  Send  and  receive  alternately  with  a  companion 
at  the  same  instrument.     (4)  Send  and  receive  with  a  companion  at  a  distant 
station.     (5)  Complete  the  practice  in  a  regular  telegraph  office.     A  good  oper- 
ator should  often  be  consulted  to  avoid  acquiring  a  faulty  sending. 

2.  To  write,  grasp  the  button  with  thumb  under  the  edge  and  first  two  fingers 
above  it;  allow  the  wrist  to  be  perfectly  limber:  rest  the  arm  on  the  table  at  or 
near  the  elbow;  let  the  grasp  be  firm  but  not  rigid;  never  allow  the  fingers  or 
thumb  to  leave  the  key  nor  the  elbow  to  leave  the  table ;  avoid  too  much  force. 
The  motion  to  be  imparted  is  directly  up  and  down,  principally  at  the  wrist. 
Guard  against  rigidity  of  the  muscles,  graduate  your  writing  to  the  capacity  of 
the  receiver  and  never  crowd  him. 


TELEGRAPHY.  121 

3.  To  receive,  always  write  with  pen  or  pencil  the  words  as  they  come  from 
the  sounder ;  do  not  attempt  to  anticipate.     A  tendency  to  anticipate  causes 
errors  and  delays  progress.     It  is  good  practice  to  have  messages  sent  backwards 
from  a  book.     Break  in  as  soon  as  a  word  is  missed  and  do  not  wait  until  several 
words  are  lost  in  tlie  hope  of  catching  a  sufficient  number  to  guess  at  the  mean- 
ing of  the  message.     Always  break  in  at  the  first  word  missed  and  telegraph 
"G  A"  and  the  last  word  received;  this  will  regulate  the  sending.     In  a  short 
time  words  like  "and,"  "the,  "etc.,  will  always  be  recognized  and  later  whole 
phrases  without  effort. 

4.  In  the  first  practice  take  the  following  exercises  in  turn :  ( 1 )  Make  dots  in 
succession  until  a  uniform  rate  of  about  120  per  minute  is  acquired.     (2)  Make 
dashes  in  succession  until  a  uniform  rate  of  about  60  per  minute  is  obtained. 
(3)  Practice  E,  I,  S.  H,  P,  6,  until  each  can  be  made  at  will  correctly.     (4)  Make 
the  spaces  uniform  in  O,  C,  R,  Y,  Z,  etc.     (5)  Be  careful  to  proportion  short  and 
long  dashes  accurately  in  T,  L,  M,  5,  0.     (6)  Avoid  leaving  too  long  space  between 
the  dash  and  the  dot  next  to  it  in  A,  U,  V,  4  and  inN,  D,  B,  8.     (7)  Practice  the 
mixed  combinations  in  F,  G,  J,  K,  Q,  W,  X,  1,  2,  3,  7,  9,  period. 

5.  Follow  "instruction  to  operators"  given  above. 


(G)  U.  S.  ARMY  AXD  NAVY  SIGNAL.  CODE. 

(1)  WIGWAG  ALPHABET. 

A - 22      J 1122      S 212  2 ...2222 

B -.2112      K 2121      T 2  3 1112 

C 121      L 221      U 112  4 2221 

D 222      M 1221      V 1222  5 1122 

E 12      N 11      W 1121  6 2211 

F 2221      O 21      X 2122  7 1222 

G 2211      P 1212      Y 111  8— 2111 

H 122      Q 1211      Z 2222  9 1221 

I....    1      R 211      1 1111  0 2112 

(2)    ABBREVIATIONS. 

a after.          n _.  not.  ur your.          xx3 "numerals 

b before.          r are.  w. word.  follow"  or  "numer- 

c can.          t the.  wi with.  als  end." 

h have.  u you.  y why.          sig.  3 signature. 

End  of  a  word 3  Repeat  last  word 121.  121.  3 

End  of  a  sentence 33  Repeat  last  message  ..  121.  121.  121.  3 

End  of  a  message _. 333  Error 12.12.3 

Aye,  "  I  understand  " 22.  22.  3  Move  to  the  right 211.  211.  3 

Cease  signaling 22.  22.  22.  333  Move  to  the  left 221.  221.  3 

(3)    CODE  CALLS. 

A.  S.  U.  Action  Signals  Use.  C.  A.  U.  Cipher  "A"  Use. 

I.  C.  U.  International  Code  Use.  C.  B.  U.  Cipher  "B"  Use,  etc. 

T.  D.  U.  Teleg.  Dictionary  Use.  N.  L.  U.  Navy  List  Use. 

G.  L.  U.  Geographical  List  Use.  V..N.  U.  Vessel's  Numbers  Use. 

G.  S.  U.  General  Signals  Use. 

(4)    INSTRUCTIONS   FOR  SIGNALING  WITH   FLAG,    TORCH,    HAND  LANTERN,  OR 
BEAM   OF  SEARCH   LIGHT. 

There  are  but  one  position  and  three  motions. 

The  first  position  is  with  the  flag  held  vertically  in  front  of  the  center  of  the 
body,  butt  of  staff  at  height  of  waist,  signalman  facing  squarely  toward  the 
station  with  which  it  is  desired  to  communicate. 

The  first  motion,  or  "1,"  is  a  motion  of  the  flag  to  the  right  of  the  sender,  and 
will  embrace  an  arc  of  90°,  starting  with  the  vertical  and  returning  to  it,  and 
will  be  made  in  a  plane  exactly  at  right  angles  to  the  line  connecting  the  two 
signal  stations. 

The  second  motion,  or  "2,"  is  a  similar  motion  to  the  left  of  the  sender. 

To  make  the  third  motion,  "front,"  or  "3,"  the  flag  is  waved  to  the  ground 
directly  in  front  of  the  sender,  and  instantly  returned  to  the  first  position. 

Numbers  which  occur  in  the  body  of  a  message  must  be  spelled  out  in  full. 
Numerals  may  be  used  in  signaling  between  stations  having  Naval  Signal  Books, 
using  the  Code  Calls. 


122  HANDBOOK   FOR   ELECTRICIANS. 

(5)    TO  SEND  A   MESSAGE. 

"To  call"  a  station,  signal  its  initial  or  "call  letter"  until  "acknowledged." 
"To  acknowledge,"  signal  "Aye,"  followed  by  its  initial  or  "call  letter." 
Make  a  slight  pause  after  each  "letter,"  also  after  each  "front." 

(6)    FOG  SIGNALS. 

To  apply  this  code  to  the  "fog  whistle "  or  "fog  horn :" 
One  (1)  toot  (about  one-half  second)  will  be  "one"  or  "1." 
Two  (2)  toots  (in  quick  succession)  will  be  "two"  or  "2." 
A  blast  (about  two  seconds  long)  will  be  "three"  or  "3." 
The  signal  of  execution  for  all  tactical  or  drill  signals  will  be  one  (1)  long 
blast,  followed  by  two  (2)  toots  in  quick  succession. 
The  ear  and  not  the  watch  is  to  be  relied  upon  for  the  intervals. 

(7)    TO  SIGNAL  WITH  FLASH  LANTERN,    HELIOGRAPH    OR  SEARCH-LIGHT  SHUTTER. 

Same  as  in  fog  signals;  substitute  "short  flash"  for  "toot,"  and  "long  steady 
flash  "  for  "blast."  The  elements  of  a  letter  should  be  slightly  longer. 

"To  call"  a  station. — Make  the  initial  or  "call  letter"  until  "answered." 
Then  turn  on  a  steady  flash  until  answered  by  a  steady  flash.  The. station 
called  will  "acknowledge"  and  cut  off  its  flash  and  the  calling  station  will  pro- 
ceed with  the  message. 

No  abbreviations  will  be  used  in  the  body  of  the  message. 

All  other  conventional  signals  are  the. same  as  for  flag  or  torch. 

(H)  ARTII^ERY  FIRING  CODE. 

T  A '=  Target  angle. 

S  A  =  Shot  Angle. 

T  A  D  23  M  45  =  Target  angle  is  23  degrees  and  45  minutes. 

F  F  =  Fire. 

C  S  =  Close  station. 

T  T  A  =  Take  target  angle. 

T  A  3  =  Target  angle  No.  3. 

2  R  F  =  No.  2  gun  is  ready  to  fire. 

R  T  A  2  —  Repeat  target  angle  No.  2. 

R  S  A  4  =  Repeat  angle  No.  4  shot. 

R  U  R  =  Are  you  ready  ? 

R  U  R  F  =  Are  you  ready  to.  fire  ? 

(I)  SETTING  UP  THE  HELIOGRAPH. 

1.  Always  spread  the  tripod  legs  wide  enough  for  a  good  base  and  press  them 
firmly  into  the  ground  so  that  the  top  is  level. 

2.  The  sun  mirror  has  a  peephole  at  the  center ;  the  station  mirror,  a  paper 
disc.     Both  in  position  on  the  bar  can  be  turned  horizontally  or  vertically  by 
tangent  screws. 

3.  When  the  sun  is  in  front  of  the  operator  while  facing  the  distant  station, 
the  sun  mirror  only  is  required;  with  the  sun  in  rear,   both  mirrors  should 
be  used,  although  a  single  mirror  may  often  be  worked  to  advantage  with  the 
sun  well  back  of  the  operator.     In  the  former  case,  the  rays  of  the  sun  are 
reflected  from  the  sun  mirror  direct  to  the  distant  station ;  in  the  latter,  they 
are  reflected  from  the  sun  mirror  to  the  station  mirror,  thence  to  the  distant 
observer. 

4.  With  one  mirror. — Attach  the  mirror  bar  to  the  tripod;  insert  and  clamp 
in  their  appropriate  sockets  the  sun  mirror  and  the  sighting  rod,  the  latter  with 
its  disc  turned  down.     Sight  through  the  center  of  the  mirror  and  turn  the 
mirror  bar,  and  raise  or  lower  the  sighting  rod  until  the  center  of  the  mirror, 
point  of  sighting  rod,  and  distant  station  are  accurately  in  line ;  then  clamp  the 
mirror  bar  firmly  to  the  tripod,  taking  care  not  to  disarrange  the  alignment. 
Turn  up  the  disc  of  sighting  rod. 

Move  the  mirror  by  means  of  slow-motion  screws  until  the  "shadow  spot" 
from  the  unsilvered  peephole  falls  upon  the  disc  of  the  sighting  rod.  The 
flash  will  then  be  visible  to  the  distant-  observer. 

The  shadow  spot  must  be  kept  in  the  center  of  the  disc  while  -signaling. 

Attach  the  screen  to  its  tripod  and  place  it,  close  to,  and  in  front  of  the  sight- 
ing disc,  so  as  to  intercept  the  flash. 


TELEGRAPHY.  123 

5.  With  tiro  mirrors. — Clamp  the  mirror  bar  diagonally  across  the  line  of 
vision  to  the  distant  station ;  clamp  the  sun  mirror,  facing  the  sun,  to  the  end 
of  mirror  bar  with  tangent  screw  attachment ;  and  the  station  mirror,  facing 
the  distant  station,  to  the  other  socket.  Stooping  down,  the  head  in  rear  of 
and  near  the  station  mirror,  turn  the  sun  mirror  by  means  of  its  slow-motion 
screws  until  the  whole  of  the  station  mirror  is  seen  reflected  in  the  sun  mirror, 
and  the  imsilvered  spot  and  reflection  of  the  paper  disc  accurately  cover  each 
other. 

Still  looking  into  the  sun  mirror,  turn  the  station  mirror  until  the  reflection 
of  the  distant  station  is  brought  accurately  into  line  with,  or  is  covered  by,  the 
imsilvered  spot  and  the  reflection  of  the  disc ;  after  this,  the  station  mirror 
must  not  be  touched. 

Now  stepping  behind  the  sun  mirror,  throw  upon  the  station  mirror  a  full 
flash  from  the  sun  mirror  so  that  the  "shadow  spot"  falls  upon  the  center  of 
the  paper  disc.  The  flash  will  then  be  visible  at  the  distant  station. 

The  shadow  spot  must  be  kept  in  the  center  of  the  paper  disc  while  signaling. 
The  intercepting  screen  should  allow  room  for  adjusting  the  sun  mirror. 

(J)  LOCATING  FAULTS. 

Most  line  faults  are  of  three  kinds — a  break,  an  escape,  or  a  cross. 

1.  The  break  may  be:  (1)  complete,  as  when  the  line  is  severed  or  a  key  left 
open,  etc. — all  instruments  in  the  circuit  cease  to  work;  or  it  may  be  (2)  partial, 
as  from  a  rusted  joint  or  a  loose  contact,  etc.,  which  increases  the  conductor 
resistance — all  instruments  work  equally  feebly  or 

not  at  all.     A  complete  break,  as  in  fig.  165,  is  found       £~~  T>  /I      ] 

by  inserting  at  either  end  a  battery,  one  side  of  which 

is  to  earth,  as  shown.     The  lineman  then  proceeds     •^r4H4UT**Hfc-r*TEh- 

along  the  line  from  the  other  side  of  the  battery  con-  165 

necting,  temporarily,  at  different  points,  the  line  to 

earth  through  the  tongue  or  galvanometer.     Near  the  battery  he  gets  the  full 

current.     If  at  any  point  he  fails  to  get  it,  he  has  passed  the  complete  break. 

It  is  important  to  note  the  current  strength  from  the  taste  or  deflection  near  the 

battery ;  if,  then,  at  any  place  it  suddenly  diminishes,  but  is  still  noticeable,  a 

partial  break  has  probably  been  passed. 

2.  An  escape  (fig.  165«)  arises  from  defective  insulation  at  some  point,  as  when 
a  bare  wire  falls  to  ground  or  touches  a  tree  or  building,  or  the  covering  of  an 

insulated  wire  is  injured,  etc.,  and  allows  a  por- 

I      f\      /I      I     "I     t*on  °^  *^e  current  on  the  line  to  escape.     Instru- 

r\/  I  ments  work  unequally.     Those  near  the  battery 

A~lr*~"ir*A'Jofr  are  stronger,  those  beyond  the  escape  are  weaker 

165a  than  usual. 

The  lineman  may  inspect  the  line  to  see  if  any 

Sole,  tree,  building,  etc. ,  has  come  in  contact  with  the  wire.   If  it  can  not  be  found 
i  this  way  he  may  open  the  line  at  some  point.     If  an  examination  at  the  bat- 
tery end  still  shows  the  escape  the  fault  is  on  the  side  of  him  towards  the  battery ; 
but  if  it  has  disappeared  the  fault  is  on  the  other  side  of  him.     He  proceeds 
accordingly  to  open  the  line  at  another  point,  having  closed  the  first. 

3.  Across  (fig.  166)  is  a  fault  caused  by  two  parallel  lines  coming  in  contact ; 
the  instruments  on  one  line  respond  to  those  in  the  other.     Inspection  of  tha 
line  may  reveal  the  fault.     Or  open  both  of  the  dis- 
tant ends.     Starting  from  the  battery  the  lineman      i  p<r  * .  .*==x=*^—*^-=^ 
opens  the  line  at  some  point ;  if  he  gets  a  current  he     77! 

has  not  reached  the  fault.  .X Jj^«4-A^-L4*"l[^ 

Generally  on  a  long  line  having  several  stations 
the  fault  is  first  located  as  between  two  stations,  166- 

from  one  of  which  a  lineman  is  sent  out. 

Periodic  tests  of  the  conductor  and  insulation  resistances  of  every  important 
line  should  be  made  regularly  and  the  results  kept  in  a  record  book. 

(K)  THE  TELAUTOGRAPH. 

(a)    DESCRIPTION,    PRINCIPLES  AND  OPERATION. 

1.  Transmitter — By  means  of  two  light  rods  attached  to,  the  transmitting 
pencil  near  its  point  the  arbitrary  motions  of  writing  or  drawing  are  resolved 
into  simple  rotative  or  oscillatory  motions  of  two  pivoted  arms,  located  on  either 
side  of  the  writing  platen.  These  arms  are  included  in  the  line  circuits  and 


124  HANDBOOK   FOR   ELECTRICIANS. 

carry  at  their  extremities  small  contact  rollers  which  move  to  and  fro  upon  two 
rheostats,  or  resistance  coils,  these  being  so  connected  through  the  arms  to  the 
line  and  to  the  source  of  energy  as  to  act  both  as  adjustable  shunts  and  as 
rheostats  in  the  line  circuits.  By  this  method  the  voltage  supplied  to  the  lin_» 
is  made  to  vary  with  the  position  of  the  pencil  upon  its  writing  platen  and 
definitely  variable  writing  currents  are  transmitted. 

2.  The  receiver  principle  is  equally  simple.     The  variable  line  currents  com- 
ing in  over  the  line  wires  are  led  through  two  vertically  movable  coils,  each 
suspended  in  a  strong  uniform  magnetic  field  by  a  well-sweep  arrangement, 
from  which  they  derive  the  name  of  "buckets." 

Each  coil  is  supplied  with  an  adjustable  retractile  spring  which  tends  to 
oppose  the  movement  of  the  coil  downward  through  the  field.  It  is  evident 
that  for  given  values  of  the  line  currents  each  coil  will  have  a  definite  position 
in  its  respective  magnetic  field,  depending  upon  the  tension  of  its  retractile 
springs.  The  vertical  motions  of  these  receiver  "buckets,"  due  to  the  varying 
line  currents,  are  used  to  cause  rotative  motions  in  two  pivoted  arms,  similar  to 
those  at  the  transmitter,  which  motions,  through  another  system  of  light  rods, 
compel  the  receiving  pen  to  exactly  reproduce  the  motions  of  the  transmitting 
pencil. 

3.  To  accomplish  the  pen-lifting  at  the  receiver  an  automatic  device  is  used, 
consisting  of  an  induction  coil  at  the  transmitter,  having  two  secondary  wind- 
ings and  performing  the  double  function  of  pen-lifting  and  reducing  friction. 
The  primary  circuit  of  this  coil  is  entirely  local  at  the  transmitter,  and  includes 
an  interrupter  and  a  shunt  circuit  controlled  by  the  platen. 

4.  The  vibratory  secondary  currents  are  superimposed  upon  the  writing  cur- 
rents, and  serve  to  keep  the  receiving  pen  in  continual  though  imperceptible 
vibration,  reducing  friction  in  the  moving  parts  to  a  minimum.     The  normal 
writing  pressure  of  the  pencil  upon  the  transmitter  platen  opens  the  shunt 
circuit  and  causes  an  increase  in  the  strength  of  the  secondary  vibrations. 
This  operates  a  vibratory  relay  inserted  in  one  of  the  line  circuits  at  the  receiver, 
opens  a  local  circuit,  and  causes  the  armature  of  the  pen -lifting  magnet  to  be 
released  and  the  pen  is  allowed  to  rest  upon  the  paper. 

5.  Lifting  the  transmitting  pencil  from  the  platen  decreases  the  strength  of 
the  vibrations,  closes  the  local  receiver  circuit,  the  pen-lifting  magnet  attracts 
its  armature  and  raises  the  pen  clear  of  the  paper. 

6.  The  shifting  of  the  paper  at  the  transmitter  is  done  mechanically  by  means 
of  the  master  switch.     The  same  motion  of  the  switch  operates  an  electro-mag- 
netic device  over  one  of  the  line  wires,  which  automatically  and  positively  shifts 
the  paper  at  the  receiver  a  corresponding  amount. 

The  paper,  5  inches  wide,  is  supplied  in  conveniently  detachable  rolls,  which 
are  mounte'd  in  brackets  attached  to  the  backboard  of  the  instrument.  For 
signaling,  a  push  button  at  the  transmitter  operates  a  call  bell  at  the  receiver. 

7.  The  transmitting  pencil  is  a  simple  adjustable  lead  pencil.     The  receiving 
pen  is  made  on  the  principle  of  the  ordinary  right-line  drawing  pen,  so  modified 
as  to  make  perfect  lines  regardless  of  the  direction  of  motion,  and  capable  of 
holding  an  ample  supply  of  ink. 

8.  The  inking  device  consists  of  a  bottle  or  supply  well,  with  a  hole  and  stopper 
for  refilling,  and  also  with  a  second  small  hole  in  the  side  of  the  well.     This  hole 
is  below  the  surface  of  the  ink,  and  the  top  of  the  well  being  corked  and  air- 
tight, the  ink  is  prevented  from  flowing  out  by  the  pressure  of  the  external 
atmosphere. 

The  small  hole  is  located  at  the  unison  point,  and  whenever  the  paper  is  shifted 
the  pen  returns  to  this  position  and  automatically  dips  its  point  into  the  ink 
which  stands  at  the  mouth  of  the  hole.  Capillary  attraction  is  sufficient  to 
completely  fill  the  pen,  and,  resting  in  the  hole  as  it  does,  the  point  does  not 
clog  up  with  dry  ink  when  not  in  use,  but  is  always  ready  to  start  writing  with 
a  full  fresh  supply. 

(b)  EXPLANATION  OF  DIAGRAM. 

1.  Transmitter. — The  motions  of  the  transmitting  pencil  A  are  conveyed 
through  the  pencil  arms  BB ",  and  pencil  arm  levers  CC'  to  contact  arms  DD', 
which  carry  contact  rollers  E  E',  these  contact  rollers  bearing  upon  the  periphery 
of  rheostats  F  F,  the  terminals  of  these  rheostats  being  connected  through 
master  switch  G  to  the  positive  and  negative  poles  of  a  suitable  source  of  elec- 
trical energy,  indicated  by  battery  H.  The  contact  arm  D'  is  connected  to  the 
right  line  through  one  of  the  secondaries  of  the  induction  coil  1,  and  through 
the  right-line  contacts  G'  of  master  switch,  when  the  master  switch  is  in  the 


167.  Telautograph,  with  Cover  Removed  to  Show  the  Working  Parts.  124 


TELEGRAPHY. 


125 


169.  Transmitter  and  Receiver. 


126  HANDBOOK    FOR    ELECTRICIANS. 

writing  position  as  shown.  The  contact  arm  D  is  connected  to  the  left  line 
through  the  other  secondary  of  the  induction  coil  /  through  the  left  line  con- 
tacts G2  of  master  switch. "  The  writing  platen  J  is  pivoted  at  K  K ,  and  when 
pencil  is  off,  the  platen  closes  upper  contacts  L  L  ,  shunting  resistance  /  around 
the  primary  winding  of  induction  coil  /.  The  vibrator  M  is  in  circuit  with  the 
primary  of  induction  coil  I  and  battery  H,  and  rapidly  vibrates,  the  current 
passing  through  the  primary  of  the  induction  coil,  thus  causing  a  vibratory 
current  to  traverse  the  right  and  left  line  wires,  the  strength  of  this  vibratory 
current  depending  upon  the  position  of  the  platen  J-,  when  this  platen  is 
depressed  by  the  pencil  in  the  act  of  writing  the  shunt  around  the  primary  of 
induction  coil  /  is  open,  consequently  the  strength  of  the  vibratory  currents"  on 
line  is  increased ;  this  increased  strength  of  vibration  actuates  the  pen-lifting 
relay  m  (in  receiver).  The  paper  at  the  transmitter  is  shifted  by  moving  the 
handle  N  of  lever  O,  which  is  connected  to  shaft  P,  which  carries  the  pawl  Q. 
engaging  the  ratchet  wheel  R,  mounted  on  shaft  of  paper-shifter  roller  S. 
Each  movement  of  this  handle  N  to  and  fro  causes  the  roller  S  to  rotate,  which 
moves  the  paper  forward.  The  shaft  P  also  carries  master-switch  contact 
plates  G,  Gl,  G2,  which  open  and  close  the  line  and  battery  circuits,  according 
to  the  position  of  handle  N;  circuits  being  closed  and  instrument  in  sending 
position  when  handle  N  rests  in  position  shown  by  arrow.  The  movement  of 
the  handle  N  in  the  opposite  direction  cuts  the  instrument  out  of  circuit.  The 
handle  is  locked  in  either  position  by  lever  P,  and  can  not  be  released  except  by 
pressing  point  of  pencil  A  on  button  T.  A  signal-switch  push  button  is  shown 
at  U;  this  switch  when  operated  throws  current  of  positive  polarity  through 
right  line,  which  rings  receiver  bell  u,  as  hereafter  described. 

2.  Receiver.  — The  motions  of  receiver  pen  a  are  caused  to  duplicate  the  motions 
of  transmitting  pencil  A  through  the  pen  arms  b  b',  pen-arm  levers  c  c  ;  which 
are  mounted  on  shafts  carrying  sectors  d  d '.     Light  metal  bands  e  e  are  attached 
to  the  peripheries  of  sectors  d  d'  and  carry  at  their  lower  ends  coils  (or  "buck- 
ets ")  //',  and  their  upper  ends  are  attached  to  springs  g  g .     The  coils  /  /  are 
movable  in  the  annular  spaces  between  the  poles  of  the  magnets  h  and  i,  and  h 
and  i'.     Coil/  is  in  circuit  with  Morse  relay  j  and  the  left  line,  and  coil/  is  in 
circuit  with  pen-lifting  relay  in  and  the  right  line.     As  the  transmitting  pencil  is 
moved  its  motions  are  transmitted  to  contact  rollers  E  E ,  the  strength  of  cur- 
rent on  line  is  varied,  the  currents  becoming  stronger  as  the  rollers  approach 
the  positive  ends  of  the  rheostats  F  F ,  these  currents  traversing  line  and  pass- 
ing through  coils//,  causing  them  to  take  different  positions  in  the  magnetic 
fields,  opposing  the  pulls  of  the  springs  g  g',  these  springs  being  so  adjusted  that 
the  position  of  the  receiving  pen  in  the  writing  field  will  always  be  the  same  as 
the  position  of  the  transmitting  pencil  on  its  writing  platen. 

3.  The  depression  of  platen  J,  causing  a  strong  vibratory  current  to  traverse 
line,  causes  the  armature  of  pen-lifting  relay  in  to  vibrate  and  interrupt  the 
circuit  of  pen-lifter  m',  thus  releasing  the  armature  of  pen-lifter  and  lowering 
the  pen-arm  rest  so  as  to  allow  the  pen  to  come  into  contact  with  the  paper. 
Upon  raising  the  transmitting  pencil  from  its  platen  the  vibratory  current  will 
be  weakened,  the  armature  of  pen-lifting  relay  m  ceases  to  vibrate,  closes  the 
circuit  of  pen-lifter  m',  which  attracts  its  armature  and  thus  lifts  the  pen  from 
the  paper. 

4.  The  paper-shifter  o'  is  an  electro-magnetic  device  and  is  controlled  by  the 
Morse  relay  j,  the  armature  of  this  relay  closing  the  circuit  of  the  shifter  through 
its  forward  contact  when  the  relay  j  is  energized  by  line  current  through  the 
master  switch  by  the  movement  of  handle  N  in  the  position  shown  by  arrow. 

6.  The  signal  bell  u,  which  is  of  low  resistance,  is  thrown  in  parallel  with  the 
right-line  coil,  or  "bucket"/'-  when  no  current  is  passing  through  the  paper- 
shifter,  consequently  when  signaling  current  passes  over  right  line  the  bulk  of 
the  current  passes  through  the  bell,  rather  than  through  coil/'. 

6.  The  ink  well  (an  ordinary  glass  bottle)  is  shown  at  p,  the  receiver  pen  a 
entering  the  opening  p '  and  receiving  a  fresh  supply  of  ink  every  time  the  paper 
is  shifted,  the  pen  resting  in  this  opening  and  in  contact  with  the  ink  when  the 
instrument  is  not  in  use. 

(c)  INSTALLING. 

The  instruments  are  furnished  with  a  suitable  backboard,  the  connections 
being  made  between  the  instruments  and  the  circuits  on  the  backboard  by  auto- 
matic contact  pins,  so  that  the  instruments  can  be  put  on  and  taken  off  readily. 
The  terminals  on  the  backboard  for  connecting  to  line  and  battery  are  plainly 
marked  so  that  the  proper  connections  may  be  easily  made. 


168.  In  Operation. 


124 


o?  THE 

UNIVERSITY 

OF 


TELEGRAPHY.  127 

(d)  OPERATION. 

1.  To  write. — Depress  button  with  pencil  point  and  pull  lever  towards  you  a 
full  stroke ;  release  button  with  lever  in  this  position,  and  write  with  firm  pres- 
sure on  paper. 

2.  To  shift  paper. — Depress  button,  holding  it  down  until  you  have  moved 
lever  back  and  forth  its  full  stroke  as  many  times  as  you  wish  to  shift  paper, 
then  release  button  with  lever  in  position  towards  you. 

3.  To  hang  up. — Depress  button,  allowing  lever  to  rest  in  position  away  from 
you.     Always,  after  writing,  leave  the  lever  in  position  from  you. 

(e)  CARE  OF  INSTRUMENTS. 


filled 
the_ 
that  purpose. 


XIV.— TELEPHONY. 


(A)   APPARATUS  AND   CONNECTIONS. 

Fig.  170  gives  details  of  the  apparatus  and  connections  of  the  bridge  form  of 
the  American  Bell  telephone : 

1.  Western  electric  call  box,  500  ohms  in  armature,  1,000  ohms  in  bell  magnets. 

2.  Long-distance  induction  coil,  1,000  ohms  in  the  secondary. 

3.  Solid  back  transmitter,  3  ohms. 

4.  Two  double-pole  watch  receivers  with  head  strap,  75  ohms  each. 

5.  A  porous  cup,  or  a  carbon  cup  Leclanche,  the  latter  preferred. 

6.  Warnock  hook. 

Full  lines  represent  electric  circuits ;  those  drawn  heavy  show  the  local  or 
transmitter  circuit. 

7.  When  one  turns  the  crank  shaft  in  the  call  box  to  ring,  a  cam  thereon  causes 
the  whole  shaft  to  slide  in  opposition  to  a  spiral  spring,  £  inch  to  the  left,  into 
contact  at  A.   The  generator's  armature  coil  is  thereby  thrown  into  circuit ;  its 
terminals  are  the  insulated  pin  B  bearing  against  a  spring  and  the  armature 
shaft  leading  the  current  to  metal  frame  and  A. 

8.  When  the  receiver  is  off  the  hook,  lever  scrapes  into  good  contact  with  both 
springs  at  F;  when  on,  it  opens  these  points.     Both  posts  of  the  watch  receiver 
T  T  are  mounted  on  a  triangular  plate  of  ebonite  inside  the  case. 

9.  Polarized  bell. — The  U-shaped,  permanent  magnet  N S  screwed  at  Nto  the 
backpiece  of  the  electro-magnet,  renders  both  poles  of  the  electro-magnet  north, 
and  by  induction,  the  middle  of  the  armature  where  it  is  pivoted,  north.     Both 
armature  ends  are,  therefore,  south;  i.  e.,  either  armature  £-end  stands  opposite  an 
AT-pole.     When  a  positive  current  enters  the  magnet  coils,  one  N-pole  is  neutral- 
ized and  the  other  is  made  stronger  so  that  the  latter  attracts  its  armature  end. 
A  negative  C  makes  the  other  jV-pole  attract  its  armature  end,  and  so  on.    As 
there  is  no  spring  to  be  overcome,  a  polarized  relay  is  very  sensitive  and  deserves 
attention  on  account  of  its  importance  in  the  service.     For  the  magneto  which 
generates  the  alternating  +  and  —  currents,  see  page  46. 

(B)   MAGNETO,  BEUL,  AND  SECONDARY  COII.S. 

The  magneto,  bell,  and  secondary  coils  of  each  station  are  joined  to  mains — 

IN  PARALLEL  OR  BRIDGE  (FIG.   171.)  IN  SERIES  (FIG.  172). 


17 i.  Parallel  Telephone  Station. 

1.  Allljells  are  permanently  bridged.    They  will 
respond  to  the  magneto's  glow  alternations  but 


172.  Series  Telephone  Station. 

The  throe  main  coils  have  few  turns  of  wire  and 
low  resistance,  and  operate  in  series. 

Magneto  circuit,  normally  short-circuital,  has 
tin  -hunt  opened  automatically  at  A  by  the  crank 
shaft  sliding  to  the  right  %  inch  when  rotated,  so 
that  the  ringing  current  goes  to  line. 


magneto's  slow 

their  impedance  acts  like  an  infinite  resistance  to 
the  rapidly  alternating  speaking  current. 

2.  Magneto  circuit,  normally  open  at  A,  is  closed 
automatically  l,v  the  rr.uik  shaft  when  rotated,  so 
that  the  generated  current  goes  to  line. 

3.  When  the  receiver  is  on  the  hook  lever  for  calling,  the  circuit  between  terminals  is— 

1.  Bells,  3.  1.  H,  L,  A,  bells,  3. 

•I.  When  receiver  is  on  and  the  crank  is  turned  to  call,  the  circuit  is— 

1.  A,  armature,  3.1  1.  H,  L,  A,  armature,  bells,  3. 

1.  Bells,  3.  I 

5.  When  the  receiver  is  taken  off  for  talking,  the  circuit  i: — 

1.  R,  S,  F,  3.     Local  circuit  is— B,  T,  P,  H,  L. 


1.  Bells,  3.|LoCftl  cirniir  N_ 

1.    ft,    /*,    O.  >        P     T     P     /•'     A 

1.  fl,  F,  3.)      *•*••'•**• 


(128) 


TELEPHONY. 


129 


„  8^rrfi 

L_    -vf> 


170.  Complete  Details  of  Bridge  Telephone. 

(Porous  cup  and  Hayden  cells  shown  ;  use  one  kind  only.) 


1714—9 


130  HANDBOOK   FOR    ELECTRICIANS. 

6.  Five  bridge  or  four  series  telephones  are  the  limit  on  one  circuit.  When 
more  are  required  (as  will  rarely  happen)  a  central  exchange  or  a  party  line  will 
be  necessary.  The  main  circuit  is  always  metallic.  On  short,  busy  lines,  as 
between  range  finder  and  four  mortar  pits,  it  will  be  advantageous  to  run  four 
main  wires — two  for  talking  and  two  for  signaling.  All  telephones  on  the  same 
circuit  must  be  alike. 

(C)    TO  USE. 

Give  the  bell  crank  one  sharp  turn,  take  the  receiver  from  the  hook,  place  it 
firmly  against  the  ear  and  when  the  unhooking  at  the  distant  station  is  heard, 
give  the  number  wanted  if  it  is  "  Central "  or  the  name  desired  if  it  is  a  party 
line. 

Speak  directly  into  the  transmitter,  with  the  lips  close  to  it,  in  a  low,  distinct, 
and  deliberate  manner ;  never  shout.  Be  guided  by  the  listener  as  to  your  dis- 
tance from  transmitter  and  your  articulation.  When  finished,  hang  the  receiver 
on  the  hook  and  give  a  half  turn  to  the  crank.  During  storms  and  when  closing 
for  the  day,  shunt  out  the  instrument  by  the  lightning-arrester  plug.  Keep  the 
instrument  free  from  dust,  the  cells  clean,  and  the  solution  at  normal  strength 
and  height. 

(D)   TELEPHONE  FAULTS   AND   THEIR  LOCATION. 

The  three  classes  liable  to  occur  are:  (1)  An  open  'circuit  at  a  joint,  post, 
spring  contact,  or  where  rust  is  seen;  (2)  a  short  circuit  in  a  magnet  coil,  cord, 
or  where  dust  and  filings  collect;  (3)  derangement  of  magnets,  bells,  switch, 
transmitter,  receiver,  or  battery. 

An  intermittent  fault  is  more  difficult  than  a  lasting  one  to  find,  as,  for  exam- 
ple, when  a  line  grounds  only  when  swayed  by  the  wind,  or  the  resistance  of  a 
joint  keeps  changing,  or  the  two  wires  of  a  cord  touch  only  when  it  is  in  a  cer- 
tain position.  To  locate  a  fault  promptly,  a  knowledge  of  the  circuit  and  experi- 
ence are  essential. 

The  first  steps  in  locating  a  fault  are  to  question  the  user,  to  look  carefully 
over  the  accessible  parts,  to  try  to  ring,  to  listen  for  the  characteristic  noise  in 
the  receiver  from  scratching  on  the  transmitter,  and  to  determine  at  once 
whether  the  trouble  is  in  the  station  or  outside  of  it  by  cutting  out  the  station  from 
the  rest  of  the  circuit  if  necessary.  The  symptoms  differ  somewhat  in  bridge 
and  series  systems.  Three  cases  arise : 

1.  Station  can  not  ring. — See  if  the  bell's  armature  is  free,  if  wire  joints  around 
bell,  hinges,  hook,  etc.,  are  good,  and  if  both  shaft  contacts  at  the  magneto 
operate.     If  a  bridge  telephone,  there  may  be  a  short  circuit  between  its  mains, 
in  which  case  the  crank  turns  with  difficulty ;  or  there  may  be  a  break  in  its 
magneto  or  its  bell  circuit,  but  not  if  the  bell  rings  after  detaching  the  line  wires. 

In  a  series  telephone,  there  is  probably  an  open  circuit ;  it  is  outside  if  the  bell 
rings  after  connecting  the  line  posts  by  a  short  wire  or  by  the  lightning-arrester 
plug.  If  in  this  case  there  is  no  ring,  the  trouble  is  in  the  ringing  circuit. 

2.  Station  can  ring  but  can  not  hear. — The  speaking  circuit  is  open  or  shunted 
at  some  point.     If  scratching  or  blowing  into  the  transmitter  is  heard,  the  sta- 
tion's receiver  circuit  must  b3  in  order  and  the  fault  probably  lies  in  the  trans- 
mitter circuit  of  the  distant  station. 

3.  Station  can  ring  but  can  not  be  heard. — The  fault  is  probably  in  the  local 
transmitter  circuit.     But  if  scratching  on  the  transmitter  is  heard,  the  fault  lies 
in  the  receiver  circuit  (receiver,  secondary  and  lever  contacts)  of  the  distant 
station. 


TELEPHONY.  131 

(E)  IN  GENERAL. 

The  usual  induction  noises  heard  in  a  receiver  show  that  the  main  line  and 
your  station  receiver  circuit  are  in  order ;  although  the  secondary  may  in  this 
case  be  short-circuited.  If  so,  blowing  into  the  transmitter  can  not  be  heard. 
To  verify,  open  the  line  and  if  the  noises  do  not  cease  their  cause  lies  within. 

Cross  talk,  humming  of  motors,  Morse  clicks,  etc. ,  show  that  the  telephone 
line  runs  parallel  with  a  foreign  wire  for  a  greater  distance  on  one  side  of  it  than 
on  the  other,  or  that  there  is  leakage  through  the  ground  terminals.  To  prevent 
these  noises,  telephone  lines  are  usually  metallic,  and  if  parallel  with  other  wires 
they  should  run  for  equal  distances  on  opposite  sides  of  them.  A  twisted  metallic 
or  a  balanced  line  has  no  induction  noises. 

Creaking  or  boiling  sounds  in  the  receiver  are  often  due  to  bad  contacts  in  the 
local  or  transmitter  circuit. 

The  set  entire  is  not  in  good  adjustment  unless  the  bell  hammer  responds 
promptly  to  slow  turning,  giving  two  strokes  to  each  turn  of  the  armature,  and 
unless  light  scratching  on  the 'backboard  is  heard  in  the  receiver.  The  receiver 
should  be  audible  to  a  good  ear  at  10  feet  distance  from  low,  distinct  talking  at 
the  distant  station. 

(F)  DERANGEMENT  OF  APPARATUS. 

1.  In  magneto. — (a)  Short  circuit  from  brass  filings,  dirt  or  burnt  coils;  (6) 
dynamo  shaft  in  the  bridge  telephone  not  closing  on  the  spring  contact  and  in 
the  series  not  opening  when  turned;  (c)  armature  shaft  not  in  contact  with 
spring;  (d)  weak  field  magnets ;  (e)  armature  striking  pole  piece;  (/)  dust  on 
lightning-arrester. 

2.  In  polarized  bell. — (a)  Armature  striking  pole  piece,  or  too  distant,  or  not 
free  to  move,  or  not  responding  promptly;  (b)  bells  not  spaced  to  receive  strokes 
alike,  in  which  case  loosen  and  turn  them ;  (c)  magnet  too  weak  to  hold  by  its 
own  weight. 

3.  In  hook  lever. — Not  scraping  into  good  contacts;  weak  spring. 

4.  In  solid  back  transmitter. — (a)  Breaking  of  mica  disc,  which  allows  carbon 
granules  to  fall  out ;  (6)  "  packing  "  of  granules,  which  renders  speech  inaudible, 
and  may  often  be  remedied  by  moving  transmitter  quickly  up  and  down ;  (c) 
diaphragm  rusted,  or  its  rubber  hardened,  or  its  spring  too  tight  or  too  loose. 

5.  In  receiver.  —  (a)  Diaphragm  too  close,  or  too  distant  from  pole  piece.     Its 
distance  is  correct  when  after  removing  ear  piece  and  holding  the  receiver  side- 
ways in  one  hand  and  tapping  with  the  other,  the  diaphragm  falls  partially  off ; 
if  it  does  not  start  it  is  buckled  or  too  close ;  if  it  falls  entirely  off  it  is  too  far 
away;  (6)  if  diaphragm  is  buckled,  replace  it;  (c)  dirt  between  it  and  the  poles; 
(d)  a  break  in  the  circuit,  discoverable  by  touching  the  ends  of  the  receiver's 
cord  to  the  poles  of  a  cell;  (e)  a  short  circuit  in  the  cord  itself  through  which 
a  series  bell  will  ring  and  a  bridge  bell  will  not. 

6.  In  battery. — See  Fuller  bichromate  and  Leclanche  cells.     One  or  two  like 
cells  in  series  usually  afford  sufficient  battery  power. 

7.  In  locating  faults,  an  assistant,  a  detector  galvanometer  with  dry  cell,  and 
such  tools  as  knife,  small  pliers,  screw  driver,  file,  and  emery  are  useful. 

8.  Guard  against  dust,    damp,   unsoldered  connections,   loose  wires  under 
screw  washers  or  binding  posts  from  shrinkage  of  wood,  breaks  or  contacts  in 
the  receiver  cord. 

(G)  INTERCOMMUNICATING  TELEPHONY 

1  Is  suitable  for  twenty  or  less  stations  near  each  other,  as  in  a  large  build- 
ing or  in  any  fort.  A  cable  having  one,  and  in  some  cases  two  more  wires  than 
the  number  of  stations,  passes  each  station.  There  is  no  central  (fig.  173). 
Any  one  station  can  be  put  into  communication  with  any  other  on  that  system 
by  the  operator  himself.  The  left  hand  figure  at  each  switch  designates  the 
number  of  station  or  instrument  to  which  the  switch  is  connected,  and  the  lever 
must  always  remain  on  left  hand  point  except  when  another  station  is  called. 
No.  1  wishes  to  communicate  with  No.  3.  He  moves  the  lever  of  his  switch  to 
the  point  marked  3,  and  after  ringing  him  up  can  carry  on  conversation. 
When  No.  1  has  finished  talking  he  replaces  the  lever  of  his  switch  fco  contact 


132 


HANDBOOK   FOR   ELECTRICIANS. 


point  No.  1.  A  similar  action  takes  place  when  any  of  the  other  stations  wish 
to  communicate.  This  system  is  specially  adapted  for  communication  in  hotels, 
factories,  office  buildings,  or  any  place  where  wires  are  all  under  one  roof. 
When  the  distance  between  the  terminal  stations  is  over  500  feet  the  expense 
becomes  high,  owing  to  the  number  of  wires  required. 


II  rU'Ih 


ill 


IV 


COMMON  RETURN 


173.  No  Central. 


2.  A  common  battery  is  a  feature  of  modern  systems.  In  fig.  174  each  of  the 
ten  lines  is  connected  with  10- springs  jacks  on  each  of  the  ten  telephones  (three 
shown).  P  is  plugged  to  the  No.  of  the  station  called,  c  and  c  are  impedance 


174.  Common  Battery,  10  Stations. 


coils  on  either  side  of  the  transmitter  circuit  to  prevent  cross  talk  when  more 
than  two  stations  communicate. 
3.  The  Holtzer-Cabot  system  is  extensively  used  (fig.  175). 


C.B. 


175. 


TELEPHONY. 
(H)    A   CENTRAL   STATION   SYSTEM 


133 


1.  Sometimes  required,  is  shown  for — 
40  line  drops,  1  per  station,  A. 
10  clearing-out  drops,  B. 
10  plugs  with  double  cords,  C. 
10  listening  keys,  E,  for  10  connections. 
10  sets  ringing' keys,  F,  for  10  connections. 


Operator's  transmitter. 
Operator's  receiver. 
Operator's  magneto. 
Night-bell  switch. 
Operator's  telephone  battery./ 


176.  Central. 

2.  On  this  board  (fig.  176)  ten  stations  can  be  put  in  communication  with  ten 
others  in  pairs  at  one  time,  by  way  of  the  ten  twin  wire  cords  (fig.  178),  kept 
from  getting  tangled  by  running  weights.    Plug  C  (fig.  176),  or  P  (fig.  178),  has 
two  insulated  metal  parts,  knob  and  cylinder,  which  are  the  terminals  of  the 
twin  wires  in  the  cord. 

The  line-drop  magnet  (figs.  177-8)  on  the  board  lets  plate  Sfall  and  thus  signals 
the  number  of  the  station  which  calls  and  desires  a  connection ;  its  wires  connect 
with  mains  to  station;  wire  u  is  for  a  night  local  call  bell  circuit. 

3.  The  "clearing-out  drop"  magnet,  C  O,  in  fig.  178,  is  like  the  line  drop  except 
in  its  winding,  of  finer  wire  (500  ohms),  soft-iron  cover  to  prevent  induction  and 
more    closely    adjusted     armature;    it    is 

bridged  across  the  two  wires  in  the  cord 
which  connects  the  two  stations  placed  in 
communication  and  will,  therefore,  signal 
when  either  station  rings  "off." 

4.  To  illustrate  the  working  of  a  board,  it 
is  only  necessary  to  take  three  line  drops, 
/,  f\  f\  in  fig.  178,  two  plugs,  P  and  P', 
and  twin  wire  cord  1  and  2,  one  listening 
key,  K,  also  one  ringing  key,  K',  whose  but- 
ton being  pressed,  throws  the  magneto,  al- 
ways running  on  a  large  board,  into  the 
circuit  of  any  pair  of  plugs. 

5.  When  plug  P  is  pushed  into  any  spring- 
jack,  as  at  a — 


177.  Gravity  Drop. 


Its  small  end  knob  raises  tip  spring  e  from  the  drop's  wire  and  joins  one  of 
the  cord  wires  with  one  of  the  mains. 


134 


HANDBOOK   FOR   ELECTRICIANS. 


The  insulated  cylinder  next  the  knob  connects  at  the  same  time  the  other, 
conductor  with  the  second  main  line  to  the  station. 

6.  Suppose  a  call  comes  from  station  1 — 

The  drop  falls,  displaying  number  "1 "  to  the  operator. 

She  then  inserts  either  plug,  as  P,  of  any  pair,  say  the  fourth,  in  the  jack, 
closes  the  listening  key,  K,  and  learns  that  connection  is  desired  with  "40;"  for 
example,  the  circuit  being  main  line,  jack  "  1,"  plug  Pand  cord,  key  K,  secondary 
and  receiver. 

She  next  inserts  the  other  plug  P'  of  pair  4,  presses  key  K '  and  rings  her  mag- 
neto, the  circuit  being  magneto  K ',  plug  P',  jack  to  "40"  and  main  line. 


178.  Three  Jacks,  Three  Drops,  One  Clearing=out  Drop. 

On  pressing  K  she  hears  station  40's  response  and  then  40  and  1  talking. 
Releasing  K,  she  may  give  attention  to  other  calls  and  connections. 

The  clearing-out  drop  C  O.  of  high  resistance  and  impedance,  being  perma- 
nently bridged  across  the  talking  circuit,  signals  when  40  and  1  have  finished. 
Their  circuit  was  main  line,  jack,  and  plug  40,  cord  twin  wire  plug,  jack  and 
main  line  1. 


XV.— LAWS,  WIRE  TABLES,  EXAMPLES. 


(A)  ELECTRICAL  QUANTITIES,  THElH  UNITS,  AND  THE 
LAWS  OF  THEIR  RELATIONS. 

Each  quantity  has  one  unit  and  every  amount  is  expressed  in  terms  of  that 
unit  by  a  decimal  number. 


QUANTITY,   SVM- 
BOL,  LAW. 

DEFINITION-. 

NAME  OF 
T.MT. 

VALUE  OF  PRACTICAL 
UNIT. 

EXAMPLES,  EQUIVA- 
LENTS. 

Difference  of 

With     electricity    pre- 

1 volt,  PD_ 

=  Hg§  of  the  PD  be- 

2 volts  PD  between  stor- 

potential, P  D. 

cisely  what  difference 

tween  the  plates  of  a 

age  plates  ;  40  volts  P  D 

V=CXK. 

of  level  is  with  water. 

Clark  cell  at  15.5°  C. 

between  arc  lamp  posts  ; 

10,000  volts   for  1-inch 

spark. 

Electro  -  motive 

Tlic  force  which  moves 

1  volt,  E  

=  i28ioftheJEJofaClark 

A  gravity  cell  has  1.1  volt 

force,  E. 

electricity  through  a 

standard    above  =  % 

E;  an  inc.  lighting  dy- 

E=CXR. 

conductor. 

of  a  Leclanche  cell. 

namo     has    about     125 

volts. 

Current 

The  time  rate  at  which 

1  ampere  __ 

=  the  C  which  deposits 

%  ampere  flows  in  a  16- 

strength,  C. 

electricity    Hows 

in    1     second     1.118 

candle  power,  110  -volt 

C=E-^-B. 

through  a  conductor. 

mgms.    of    silver  or 

lamp  ;  10  amperes  in  arc 

other  metal   equiva- 

lamp. 

lent. 

Resistance,  B  

That  property  of  a  con- 

1 ohm  

=  Res.   of    a    mercury 

1  mile  trolley  has  3  ohms; 

R  =  E+C. 

ductor  which  opposes 

(true.) 

column    1    sq.    mm. 

1,000'  cop.  wire,  1  mil. 

the  passage  of  elec- 

cross section  and  106.3 

diam.    has   1   ohm  ;    16- 

tricity. 

cms.  long  atO°  C. 

candlepower  lamp    fila- 

ment hot,  200  ohms. 

Quantity,  Q  __. 

The    total    amount    of 

1  coulomb  _ 

=  the   quantity    deliv- 

To deposit  1  pound  copper 

Q  =  CXT. 

electricity  which 

ered  by  1  ampere  in  1 

requires   1,500,000   cou- 

flows in  a  given    T 

second. 

lombs. 

(seconds). 

Capacity,  K  

Measured  by  the  Q  re- 

1 farad  

—  K  of  container  if  1 

1     microfarad  =  one  -  mil- 

K =  *Q  +  E. 

quired   to    raise  the 

conlomb  raises  its  po- 

lionth  of  a  farad  =  ca- 

container's potential 

tential  1  volt. 

pacity  of  %  mile  ocean 

1  volt. 

cable. 

Work    TI' 

The  product  of  a  force 

1  joule 

=  1    volt-c  o  n  1  o  m  b  =• 

%  ampere    in    110-  volt 

W=EXQ 

into  a  path  ;   also  of 

work    of    1    ampere 

lamp  for  1  minute  does 

=  C*RT. 

quantity  into  poten- 

through 1  ohm  in  1 

3,300    joules  ;    power  = 

tial. 

second=0.7373ft.lbs. 

55   watts;    heat  =  1,375 

calories. 

Power    P 

The  time  rate  of  work. 

1  watt 

=  P  when   1    joule  is 

1  kilowatt  =  1,000  watts  ; 

P=TF-=-r. 

A   horse   pulling    75 

done  uniformly  in  1 

1    horsepower=  746 

(T  in  sees.) 

Ibs.    at  5   miles   per 

second.    Watts  = 

watts;     1    kilowatt  =  | 

hour  exerts  1  horse- 

volts X  amperes  = 

horsepower,  approx. 

power. 

amperes  2  X  ohms. 

Heat    H 

772.55  ft.  Ibs.  work  will 

1  calorie  

:  —  H  required  to   raise 

1  calorie  =  4.16  joules  =  3 

#=.24  E  Q 

raise  1  Ib.  water  1°  F. 

1  gm.  water  1°  C.  at 

ft.  Ibs.;  1  joule  =  0.24 

=  .24  CIP  T. 

at  60°  F.  ,  London  sea 

0°  C.  =  1  gm.  deg.  C. 

calorie. 

level. 

=  0.004  Ib.  deg.  F. 

1  inch  =  2.54  centimeters. 
1  meter  =  3.28  feet. 


1  megohm  =  1  million  ohms 
1  micro.  =  1  millionth. 


1  kilo  =  1,000. 
1  milli.  - 


(B)  RULES,  LAWS,  AND  EXAMPLES. 

I.— If  a  current  should  flow  through  the  forefinger  of  the  right  hand,  in  the 
direction  in  which  the  finger  points,  the  north  end  of  a  magnetic  needle  in  the 
position  of  the  thumb  will  point  in  the  same  direction  as  the  thumb  held  perpen- 
dicularly to  the  finger.  (Figs.  180-1.} 

II. — OHMS  LAW. — In  every  electrical  circuit  the  strength  of  the  current  in 
amperes  flowing  uniformly  is  equal  to  the  electro-motive  force  of  the  generator 
in  volts  divided  by  the  total  resistance  of  the  circuit  in  ohms.  Or,  C  =  E  -+-  R. 

III.— The  difference  of  potential  between  the  ends  of  a  conductor  of  a  current 
(or  the  E.  M.  F.  in  it)  equals  the  product  of  the  strength  of  the  current  by  the 
resistance  of  the  conductor.  Or,  E  =  CR. 

(135) 


136 


HANDBOOK   FOR   ELECTRICIANS. 


IV. — The  resistance  of  a  conductor  varies  directly  ivith  its  specific  resistance 
and  length  and  inversely  with  its  cross  section  or  with  the  square  of  its  diameter. 

V. — The  resistance  of  two  or  more  wires  joined  in  series  equals  the  sum  of 
their  separate  resistances. 


180,  and  181.  Magnetic  Whirlwind  around  a  Current. 

VI. — The  total  resistance  of  two  or  more  wires  joined  in  parallel  equals  the 
reciprocal  of  the  sum  of  their  separate  reciprocals. 


fl 


R  =  If  ohm  between  A  and  5. 
Example. 

VII. — The  electro-motive  force  of  a  battery  is  equal  to  the  E  of  one  cell  multi- 
plied by  the  number  of  cells  in  series. 

Ex.  To  find  the  E  and  R  of  four  different  batteries  formed  in  turn  from  six 
gravity  cells  of  1  volt  and  3  ohms  each,  connected  up  (1)  all 
in  parallel,  (2)  all  in  series,  (3)  three  in  series  and  two  in 
parallel  and  (4)  two  in  series  and  three  in  parallel,  thus : 


6  volts,  18  ohms. 


3  volts,  4V£  ohms. 


2  volts,  2  ohms. 


VIII.  —  To  obtain  the  strongest  current  with  a  given  number  of  cells  through  a 
given  external  resistance,  arrange  the  cells  in  such  a  way  that  the  internal  resist- 
ance shall  be  as  nearly  equal  as  possible  to  the  external  resistance. 

Ex.  For  an  external  E  of  18  or  more  ohms,  the  six  gravity  cells  above  should 
be  in  series  ;  for  3  ohms  external  R,  arrange  cells  two  in  series  and  three  in  par- 
allel, and  so  on. 

IX.  —  Each  one  of  two  or  more  parallel  wires  carries  that  part  of  the  main  cur- 
rent which  the  reciprocal  of  its  resistance  bears  to  the  sum  of  the  reciprocals  of 
all  the  resistances. 

Ex.  A  generator  of  18  volts  and  3  ohms,  two  leads  of  If  and  3  ohms,  and  two 
branches  of  4  and  2  ohms  are  connected,  as  shown.  Find  Rs,  C's,  and  JE"s. 

Resistance  between  A  and  B  =1  +  (£  +  £)=  -|  ohm.  Total 
R  in  circuit  =  |4-3  +  3  +  £  =  9  ohms.  Main  C  =  18  +-  9  =  2 
amperes.  C  in  wire  4  =  2  X  (i  -*-  i)  =  f  ampere  ;  C  in  wire  2 
=  2  X  (i  •*-  i)=  t;  sum  of  C's  in  both  branches  =  2  amperes. 
P  D  of  generator  on  open  circuit  =  18  volts;  on  closed  cir- 
cuit =  2x6  or  18  —  2x3  =  12  volts.  Of  E  =  18  volts  of  the 
generator,  6  volts  are  used  to  overcome  its  own  resistance,  6 
volts  to  maintain  the  2-ampere  current  in  lead  3,  y  volts  in  lead,  1£  and  £  volts 
in  the  two  branches. 

„_  Ex.  E  R  of  branches  2,  3,  6  =  1  ohm.     Total  R  =  8  ohms.    C  =  2 

,  -  -  -   amperes.     C  in  branch  2  =  1  ampere,  in  3  =  £  ampere,  in  6,  $  ampere. 
Eight  volts  used  in  battery  ;  4  volts  in  lead  2  ;  2  volts  in  branches 
and  2  volts  in  lead  1.     Total,  16  volts. 

P  D  between  ends  of  wire  2  =  1x2  =  2  volts. 
P  D  between  ends  of  wire  8  =  £  x  3  =  2  volts. 

X.  —  TJie  quantity  of  heat  in  calories  produced  in  a  conductor  is  equal  to  the 
continued  product  of  T2^,  the  square  of  the  current  in  amperes,  the  resistance 
of  the  conductor  in  ohms  and  the  time  in  seconds.     Or,  H=  0.24  C2  R  T. 

Thus,  10  amperes  flowing  through  a  fuse  of  i  ohm  for  1  minute  generates 
360  calories  =  1.44  Ib.  deg.  Fahr.  Power  =  25  watts. 


182. 


183- 


LAWS,    WIRE   TABLES,    EXAMPLES. 


137 


XI.  —  The  power  in  watts  in  any  live  wire  or  circuit  equals  the  total  volts 
multiplied  by  the  amperes  or  the  square  of  the  amperes  times  the  ohms.     Or, 
P  =  EC=C*  R. 

Ex.  A  storage  battery  of  55  cells  in  lighting  eighty  110-volt  lamps  falls  from 
112  volts  on  open  circuit  to  110,  while  the  ammeter  shows  40  amperes.  How  is 
the  power  expended? 

Ans.:  In  each  lamp,  110  X  I  =  55  watts;  in  external  circuit,  402X  110  -4-40  = 
4400  watts;  in  battery  (112—110)  40  =  80  watts;  in  entire  circuit,  112x40  = 
4480  watts. 

XII.  —  The  grams,  W,  of  metal  deposited,  or  gas  freed,  or  electrolyte  decom- 
posed by  C  amperes  in   T  sees,  is  W  =0.000010384  C  T  Z.     Z  is  the  chemical 
equivalent  of  the  metal,  etc. 

(C)    WIRING  TABLE. 


1.  COPPER  WIRING  OF  U.  S.  UNDERWRITERS. 

Computed  from  —  Weight  1  cubic  foot  copper  =  555  Ibs.,  and  resistance  1  mil.  foot  commercial  soft  copper, 
^  pure,  at  68°  F.  =  10.367  international  or  true  ohms. 


j 

| 

Capacity. 

1 

O 

c 

5 

& 

4 

1 

o 

p 
II    . 

a 
|S 

* 

£ 

18 

§ 

1 

i 

"3 

1 

48 

|| 

al 

^o 

•"^  ai 

8  "S 

a>  ® 

. 

pq 

g 

P 

g* 

I* 

|1 

I1 

li 

.23 
00  o 
•g 

PQ 

* 

_ 

•= 

•3 

sS  £A 

§V 

0 

% 

03 

'g 

o 

1 

S 

1 

i* 

11 
^ 

« 

3 

S 
2 

PH 

g 

5 
£ 

6 

js 

i. 

II. 

III. 

IV. 

V. 

VI. 

VII. 

VIII. 

IX. 

X. 

18 

40 

1,624 

5 

3 

6.  3880 

4.92 

18 

49 

Working  formula 

17 

45 

2,  048 

6 

4 

5.  0660 

6.20 

21 

58 

for  res.  of  I  feet 

16 

51 

2,583 

8 

6 

4.  0176 

7.82 

25 

65 

cop.  of  d  mils.  diam. 

15 

57 

3,257 

10 

8 

3.1860 

9.86 

31 

72 

10.4  XI 

14 

64 

4,106 

16 

12 

2.  5266 

12.44 

38 

83 

R  =  —  —  — 

13 

72 

5,178 

19 

14 

2.0037 

15.68 

43 

. 

12 

11 
10 

81 
91 
102 

6,530 
8,234 
10,  380 

23 
27 
32 

17 

21 
25 

1.  5890 
1.  2602 
.  99948 

19.77 
24.93 
31.44 

48 
64 
80 

4-18 
4-17 
4-16 

109 
129 
134 

Res.  increases  0.21 
per  cent  for  1°  F. 
rise  of  temperature. 

9 

8 

114 

128 

13,  090 
16,510 

39 
46 

29 
33 

.  79242 
.  62849 

39.  65 
49.99 

97 
116 

8-18 
8-17 

148 
165 

Res.  H.  D.  cop- 
per  ==  1.0226  X  soft 

7 
6 
5 
4 
3 
2 
1 
0 
00 
000 
0000 
Cables. 

144 

162 
182 
204 
229 
258 
289 
325 
365 
410 
460 
630 
727.3 
814.5 
891.9 
963.9 
1030.  5 
1092.  6 
1152 
1208.  7 

20,  820 
26,  250 
33,100 
41,  740 
52,  630 
66,  370 
83,  690 
105,  600 
133,  100 
167,  800 
211,  600 
300,000 
400,000 
500,000 
600,000 
700,000 
800,000 
900,000 
1,000,000 
,100,000 

56 
65 
77 
92 
110 
131 
156 
185 
220 
262 
312 
405 
503 
595 
682 
765 
846 
924 
1000 
1075 

39 
45 
53 
63 
75 
88 
105 
125 
150 
181 
218 
273 
332 
390 
440 
488 
540 
585 
630 
675 

.  49845 
.  39528 
.  31346 
.  24858 
.  19714 
.  15633 
.  12398 
.  09827 
.  07797 
.  06184 
.04904 
.  03355 
.  02516 
.  02013 
.  01666 
.  01438 
.  01258 
.01118 
.01006 
.00915 

63.03 
79.49 
100.23 
126.  40 
159.  38 
200.98 
253.  43 
319.  74 
402.  97 
508.  12 
640.  73 
932 
1242 
1553 
1863 
2174 
2474 
2795 
3106 
3416 

118 
166 
196 
228 
265 
296 
329 
421 
528 
643 
815 

|| 
P 

8-16 
16-18 
16-17 
16-16 
32-18 
32-17 
32-16 
32-15 
32-14 
32-13 
32-12 
37-090 
37-1039 
61-0905 
61-0991 
61-1071 
61-1145 
61-1214 
61-128 
61-1343 

180 
203 
220 
238 

259 

300 
340 
380 
425 
454 

For  actual  cross- 
section    multiply 
Nos.in  III  by  0.7854. 
For  ohms  per  mile 
multiply  Nos.  in  VI 
by  5.28. 
Nos.    in  VI    give 
also  volts  fall  of  po- 
tential per    ampere 
per  1,000  feet. 
From  III  we  can 
get     equivalent 
strand  cable  for  any 
wire.     Four  No.  3's 
may  replace  one  0000 
wire    because    4   X 
52630    =   nearly 
211600.     For  No.  0, 
take  two  No.  3's  or 
four  No.  6*s. 

1262.  8 

,  200,  000 

1147 

715 

.00838 

3727 

.2  "3 

91-1148 

1314.  5 

,  300,  000 

1217 

755 

.00769 

4038 

"eS   4J 

91-1195 



1364 

,400,000 

1287 

795 

.00715 

4348 

1     » 

91-124 



1413.  5 

,  500,  000 

1356 

835 

.00667 

4658 

•-J! 

91-1285 

1458.  6 

1,  600,  000 

1423 

875 

.00625 

4968 

91-1326 



1503.  7 

1,700,000 

1489 

910 

.00588 

5278 

C    *w 

91-1367 



1547.  7 

1,800,000 

1554 

945 

.  00556 

5588 

t-2 

127-1195 



1571.9 

1,900,000 

1618 

980 

.00527 

5898 

•s 

127-1223 

1630.  2 

2,000,000 

1681 

1015 

.00500 

6208 

127-1254 

__l 

Rough  rule. — One  thousand  feet  of  soft  copper,  one  mil.  in  diameter  (No.  10) 
has  one  ohm  resistance  at  the  ordinary  temperature  of  a  room. 


138 


HANDBOOK   FOR   ELECTRICIANS. 


2.  TABLE  FOR  TAPS,  BRIDGE  WIRES,  ETC.,   OF  NEGLIGIBLE  DROP  (0.15  OF  1 

PER  CENT  OR  LESS.) 


Wire  Nos                                     —       

0 

1 
200 

lit,*') 

2 

:-!       4 

5 

6 

7 

8 

10 

12 

14 

Lamp  (  52  v                             _                 - 

300 
1280 

2(10 
860 

160    130 
680    560 

too 

4:r, 

80 
34fi 

66 

280 

50 

±20 

39 
160 

24 
100 

15 

tio 

!•         H 

Feet   (110  v 

3.  TABLE  OF  SIZES  OF  SAFETY  FUSES. 

Fuse  wires  should  be  stamped  with  80  per  cent  of  the  maximum  amperes 
which  they  can  carry  indefinitely,  thus  allowing  £  overload. 


Amperes  carried 

Diaiii.  in  mils 


60  7jd  8%  11 

40  45  50   60 


90 


24     30 
100    110 


HIM 


ISO 


80  100 

-00  --0 


In  testing,  allow  naked  open  fuses  five  minutes  to  blow ;  inclosed  fuses  not  in 
contact,  a  shorter  period. 


C=  amperes. 


k= 


E=  volts. 

P=  watts. 

H  P=  horsepower. 

C  P=  candlepower. 


(D)  GENERAL  FORMULA. 

?i=No.  lamps  in  parallel. 
c=  amperes  in  1  lamp. 
e=volts  in  1  lamp. 
?=feet  on  one  side  of  circuit. 
d=  diameter  of  wire  in  mils. 
v—  volts  lost  in  wires. 


motor  efficiency, 
ratio  output  to  input. 
0.75  in  1  h.  p.  motors. 
0.80  in  5  h.  p.  motors. 
:0.90  in  10  h.  p.  motors. 
=0.95  in  50  h.  p.  motors. 

I,— Ohm's  law.—C=E  H-  R;  E=C  R;  R=E  -h  C. 

2.—  P=C*R=CE=E*+R.     I  JJP=PH-746=C"^746. 

3.  (a)  Given  the  length,  I  in  feet  and  diameter,  d,  in  mils,  of  copper  wire,  to 
find  its  resistance  at  the  same  temperature  ;  R=l  X  10.4  -^-  d'2. 

(6)  Given  the  resistance,  R,  of  copper  or  other  pure  metal  at  t'  °  F.,  to  find 
its  R  at  any  other  temperature  t°  F  ;  R=R'  [1  +  0.0021  (t—t1)]. 

Ex.  From  the  table  the  R  of  1,000'  No.  13,  at  68  F  =2  ohms-  at  60°  F.=2 
(1  —  0.017)  =1.97  ohms;  at  100°  F.=2.13  ohms. 

4.  Given  the  voltage  and  candlepower  of  an  incandescent  lamp  to  find  the 
current  strength  to  light  it :  c  =  C  P  X  3.5  -s-  e. 

Ex.  A  32-candlepower,  52-volt  lamp  requires,  therefore.  2.15  amperes.  A 
16-candlepower,  110-volt  lamp  requires  |  ampere. 

5.  To  find  the  size  of  copper  wire  for  feeders,  mains,  branches,  service  wires, 
or  inside  work  to  feed  n  lamps  in  parallel  taking  each  c  amperes  from  a  center  of 
distribution  distant  I  feet,  so  that  the  total  drop  in  both  wires  will  be  v  volts : 


With  the  value  of  d2  found,  look  in  column  III  of  the  table  for  the  next  higher 
value.  If  this  wire  has  the  carrying  capacity  in  open  (IV)  or  concealed  (V)  work, 
as  the  case  may  be,  it  is  taken ;  if  not,  the  next  larger  wire. 

Ex.  What  gauge  of  copper  wire  will  supply  fifty  110- volt,  16  candlepower 
lamps  at  150  feet  distance  from  the  center  of  distribution  with  only  2  volts  loss? 

Ans.:  c=16  X  3. 5 -=-110  =  0.51  ampere,  d2  =  50  X  0.51  X  300  X  10.4-^2  =  39780 
circular  mils. ,  No.  4  B  and  S. 

6.  Given  the  voltage  e  delivered  to  a  lamp  and  the  per  cent  drop  (p  as  a  whole 
number)  in  the  wires  of  the  voltage  received  to  find  the  number  of  volts  drop 
in  the  wires : 

v  —  pe-^-  (100— p). 

Ex.  The  leads  to  a  cluster  of  110-volt  lamps  are  figured  for  a  4  per  cent  drop. 
What  is  the  actual  number  of  volts  lost  in  the  leads? 

Ans.:  v  =  4  X  110  -f-  96  =  4.6  volts.     Voltage  at  supply  end  =  114.6. 

Ex.  What  size  of  wire  will  carry  with  a  2  per  cent  drop,  30  amperes,  200  feet 
to  a  220  volt  motor  ? 

Ans.:  v  =  2x  220  -s-  98  =  4.5  volts  drop.  <Z2=  30  X  400  X  10.4  -f-  4.5  =  27733,  No. 
5  B  and  S. 

Ex.  Conversely,  to  find  the  per  cent  drop  in  the  wires  when  the  volts  drop 
and  volts  delivered  are  given : 

p=  100  v-t-  (e  +  v). 


LAWS,    WIRE   TABLES,    EXAMPLES. 


139 


Suppose  there  are  6  volts  drop  or  loss  in  the  leads  to  a  104- volt  cluster  or 
motor ;  the  per  cent  drop  in  the  leads  =  100  X  6  -r-  (104  +  6)  =  5.56  per  cent. 

7.  To  find  the  volts  loss  in  a  given  copper  wire  carrying  a  given  current : 

TI  X  c  X  2  I  X  10  4 
v  =  —      — -p—       —  ;  or  multiply  the  number  in  column  VI  of  the  table  by  the 

feet  and  amperes  and  divide  by  1,000. 

8.  To  find  the  sizes  of  feeder  and  mains  in  fig.  184,  which  give  a  drop  or  loss 
between  feeder  switch  and  the  32  16  candlepower  lamps  of  2  volts  or  less,  lamp 
voltage  to  be  as  nearly  uniform  as  possible. 

On  the  plan  mark  all  centers  of  clusters  and  measure  along  the  wires  the  dis- 
tances in  feet  between  them.     C  is  the  heaviest  main,  having  10  X  33  =  330  lamp 
feet.     Its  10  lamps  are  supplied  over  33  feet 
of  main  and  100  feet  of  feeder.    For  a  starter, 
consider  at  first  the  drops  to  be  in  propor- 
tion to  the  lengths,  i.  e.,  0.5  volt  in  the 
main  and  1.5  in  the  feeder. 

A  1.5- volt  drop  gives  for  the  feeder 
d-  =  32  XiX  200X10.4  -5-1.5=22187,  or  No.  6 
wire.  But  No.  6  causes  a  drop  of  1.3  volts 
either  from  (5)  or  from  the  proportion 
1.5  X  If  =  1.3,  using  in  the  fraction  the  first 
two  figures  only  of  d  '2  as  approximate. 
Therefore,  the  drop  in  all  mains  will  be  T77 
volt  or  less. 

For  main  C,  d'2=10  X  iX  66  X  10.4  -=-  0.7  = 
4903,  or  No.  13. 

Likewise  No.  13  is  found  for  the  main  to 
the  8  lamps  in  A,  40  feet  from  center. 

No.  16  for  B  and  No.  14  for  D.  Column 
V  shows  all  five  wires  to  have  sufficient  car- 
rying capacity. 

For  a  check,  use  column  VI,  which  gives 
the  volts  drop  per  ampere  per  1,000  feet. 
For  example,  in  feeder,  drop  =  0.395  (No.  6) 
X  T  (ft-)  X  16  (amperes)  =  1.3  volts;  in 


184.  How  to  Find  Sizes  of  Conductors. 


main  C,  drop  =  2  X 0.066  X  5  =  0  66  volt;  in  A,  0.64;  in  B,  0.64;  in  D,  0.63.     Be- 
tween FS  and  the  ends  of  the  four  mains  the  losses  are  1 . 96 , 1 , 94, 1 . 94,  and  1 . 93  volts. 

If  a  problem  gives  the  drop  in  per  cent,  find  the  volts  from  v  =pe  -r-  (100 — p) 
and  proceed  as  above.  In  extensive  wiring,  tables  computed  from  above 
formulas  are  used. 

Any  tap  off  the  main  D,  for  instance,  having  a  drop  greater  than  0.07  volt 
would  cause  the  total  to  exceed  2  volts.  For  this  limit,  one  lamp  at  50  feet  dis- 
tance requires  a  No.  11  wire.  But  the  sizes  of  tap  wires  may  usually  be  taken 
from  table  page  138. 

9.  To  find  d'2  of  copper  required  to  transmit  HP  (horsepower),  I  feet,  with  v' 
volts  loss  in  the  wires  to  a  motor  of  e  volts  and  k  efficiency : 

da  _  H P X  746  X  2 1  X  10.4 
v  Xe  X  k 

Then  increase  d 2  by  50  per  cent  for  overloading  and  look  in  the  table. 

Ex.  A  110-volt  hoist  motor  of  12  horsepower  is  100  feet  from  the  closet  switch. 
Select  the  tap  wires  to  allow  only  4  volts  drop  from  switch  to  motor  whose  effi- 
ciency is  90  per  cent. 

Ans.:  d'2=  47020.     Add  50  per  cent  and  the  wire  is  No.  1. 

.     10.  The  volts  required  for  a  constant  current  motor  of  H  P  (horsepower)  and 
k  (efficiency)  are,  E  =  746  X  H  P-r-  C  k. 

The  amperes  required  for  a  constant  potential  motor  of  H  P  (horsepower) 
and  k  (efficiency)  are,  C  =  746  X  HP+  Ek. 

Ex.  The  current  to  be  supplied  to  a  220-volt  motor  of  90  per  cent  efficiency  to 
get  12  horsepower  is  C  =  746  X  12  -f-  220  X  0.90,  or  45  amperes. 

11.  The  insulation  resistance  of  a  wiring  system,  including  dynamo,  or  of  any 
part  thereof,  should  be  above  10,000,000  ohms,  divided  by  the  total  amperes  to 


flow  in  the  circuit  or  in  the  part  considered.     Or,  I R  — 


10,000,000 


ohms. 


Ex.  The  I E  of  an  80-ampere  installation  is,  then,  125,000;  of  a  branch  supply- 
ing ten  16-candlepower,  110-volt  lamps  is  2,000,000  ohms. 


140 


HANDBOOK    FOR   ELECTRICIANS. 


12.  To  find  the  H  P  expended  in  a  wire,  H  P  =  C2  R  -+-  746. 

Ex.  An  arc  light  10-ainpere  current  flows  in  a  10-mile  circuit  of  No.  6  B.and 
S.  R  =  0.395  X  5-.  28  X  10  =  20.8.  The  H  P  lost  is  100  X  20.8  -r-  746  =  2.8.  ' 

13.  A  storage  battery,  motor  or  arc  lamp  supplied  by  a  generator  E  exerts  a 
back  electro-motive  force  e  in  the  circuit.     The  effective  E.  M.  F.  is  then  E — e 

T7f    0 

and  the  current,  C  =  — -^ — 

Ex.  1.  Consider  in  simple  circuit  a  dynamo  of  3  volts  and  0.02  ohm,  a  storage 
cell  of  2  volts  and  0.005  ohm,  leads  of  0.1  ohm  and  compute  what  ammeter  and 
voltmeter  should  show. 

Ans. :  C  =  8  amperes ;  drop-in  leads  =  0.8  volt ;  PD  between  dynamo  posts  3  — 
8  x  0.02  =  2.84  volts;  PD  between  cell's  posts  =  2.84  —  0.8  =  2.04  volts  =  (for  a 
check)  2  +  0.005  X  8. 

Ex.  2.  What  is  the  E  of  a  dynamo  of  0.02  ohm  supplying  100  amperes  to  54  cells 
in  series  of  2.3  volts  B.  E.  M.  F.  and  0.0004  ohm  each,  the  leads  having  0.03  ohm '.' 
Also  P  Z>'s  at  dynamo  and  battery  terminals? 

Ans.:  E  =  (54  X  2.3)  +  100  (0.02  +  0.03  +  54  X  0.0004)  =  131.4  volts.  PD  =  129.4 
and  126.4. 

Ex.  3.  A  dynamo  of  135  volts  and  0.015  ohm  was  charging  for  seven  hours 
through  0.025  ohm  leads,  53  cells  each  of  0.0002  internal  resistance  and  of  2. 1  volts 
at  starting  and  2.35  at  end  of  run.  Find  B.  E.  M.  F.,  current  and  regulator 
resistance  to  keep  C  at  200  amperes  at  starting  and  stopping. 

Ans.:  At  starting  e  =  111.3,  C  =  460,  R  =  0.068;  at  end  of  run,  e  =  124.6, 
C  =  206  R  =  0.00165. 

Ex.  4.  What  must  be  the  E  of  a  dynamo  of  0.02  ohm  resistance  in  order  to 
supply  through  0.005  ohm  leads,  7  brake  HP  to  a  motor  of  90  volts  back  E.  M.  F., 
0.025  ohm  internal  resistance  and  300  watts  internal  friction,  etc.? 

Ans.:  C  X  90  H-  300  X  746  .  \  C  =  61.4  amperes,  E  =  90  +  61.4  (0.02  +  0.005  + 
0.025)=  93.1  volts.  If  E  of  dynamo  be  raised  to  95  volts,  the  motor  will  develop 
11.6  .fiT  P. 

Ex.  6.  The  0. 11  ohm  leads  from  a  50-vplt  P  D  source  are  carrying  10  amperes  to 
an  arc  lamp  of  39  volts,  B.  E.  M.  F.,  which  has 0.09 ohm  in  the  lamp  coil,  0.08  and 
0.12  ohm  in  the  carbons  and  0.1  ohm  in  the  arc.  What  is  the  extra  resistance 
which  keeps  the  current  in  the  lamp  at  10  amperes? 

KA qq 

Ans.:  Total Pv=      ^      =1.1  ohm.    1.1  — [0.11  +  0.09+  0.08  +  0.12  +  0.10]  = 


0.6  ohm. 


10 


XVI.— ELECTRICAL  MEASUREMENTS  AND  TESTS. 


The  apparatus  required  in  the  order  of  utility  are :  A  portable  Weston  volt- 
meter (150 — 3  volts) ;  an  inexpensive  upright  Weston,  in  a  square  hard-wood  box, 
having  0  at  middle,  movable  coil  of  about  60  ohms,  both  a  shunt  and  series 
coil  to  it  such  that  two  or  three  Leclanches  will  deflect  the  needle  to  the  scale 
end  with  either,  and  connections  permitting  the  use  of  the  movable  coil  alone 
or  with  the  shunt  or  series  coil ;  a  London  P.  O.  bridge ;  a  few  fresh  dry  cells ; 
a  Weston  milli-amineter  with  shunts  for  heavy  currents ;  and,  if  at  hand,  a 
storage  battery  and  the  switch  board  instruments. 

CARE  IN   HANDLING  INSTRUMENTS. 

Do  not  send  a  current  through  a  galvanometer,  ammeter,  or  voltmeter  with- 
out first  knowing  its  direction,  and  roughly  its  strength.  Verify  by  striking 
with  one  of  the  galvanometer  leads  before  closing  for  a  reading. 

Clean  metallic  connections  which  scrape  into  contact  are  always  made. 

Set  down  an  instrument  of  any  kind  gently. 

If  the  needle  is  pivoted,  tap  the  case  lightly  before  taking  a  reading — especially 
if  the  reading  is  small. 

The  pointer  should  stand  at  zero  when  there  is  no  current. 

A  mirror  beneath  the  pointer  aids  in  getting  a  proper  reading.  To  read, 
place  the  eye  over  the  end  of  the  pointer  so  that  the  pointer  covers  its  reflection. 

When  the  box  rheostat  is  used,  be  sure  that  all  plugs  remaining  in  the  box 
make  such  good  connections  as  to  cut  out  their  coils. 

Turn  the  plug  clockwise  both  in  plugging  and  unplugging  to  keep  the  con- 
tact surfaces  scraped,  and  never  carry  the  plugs  in  the  hand  or  lay  them  in  a 
dusty  place. 

If  a  galvanometer  is  not  at  hand,  a  telephone  receiver  or  a  telegraph  relay 
may  take  its  place  in  rough  testing  and  the  tongue  for  contimiity. 

A  magneto  series  bell  whose  capacity  is  known,  is  convenient  and  useful  in 
continuity  and  insulation  tests. 

Use  a  knife  switch,  not  a  contact  key,  to  close  a  testing  circuit. 

The  current  from  a  storage  battery  ought  not  to  exceed  12  amperes  per  square 
foot  of  positive  plate  surface,  counting  one  side. 

The  dynamo  or  battery  which  furnishes  the  testing  current,  must  be  well  insu- 
lated and  care  be  taken  not  to  short-circuit  the  generator  or  to  heat  a  testing  coil. 

A  Siemens  detector  galvanometer  having  a  coarse  and  a  fine  wire  coil,  although 
not  so  good  as  the  Weston  described,  is  more  useful  than  a  magneto  in  testing. 
For  a  cheap  W.  B.,  string  a  G.  S.  wire  of  about  8  ohms  up  and  down  a  hard-wood 
board  30  inches  long,  on  which  brass  pieces  are  screwed  as  in  fig.  187 ;  for  the 
third  side  procure  a  few  coils  of  known  R. 

I. — To  measure  the  strength  C  of  a  current. — Insert  in  the  circuit  an 
ammeter  of  sufficient  capacity  and  of  such  low  resistance  as  not  to  alter  essen- 
tially the  quantity  to  be  measured.  Good  connections  are  specially  required. 

II. — To  find  the  difference  V  of  potential  between  two  given  points  of  an  elec- 
tric circuit. — Hold  the  positive  voltmeter  lead  on  the  higher  point  and  strike  the 
other  with  the  negative  lead  to  verify  the  proper  swing — both  direction  and 
amount — of  the  needle.  Then  hold  the  latter  down  and  read.  A  high  voltmeter 
resistance  is  required  so  as  not  to  alter  appreciably  the  quantity  to  be  measured. 

III. — To  test  the  continuity  of  a  circuit  by  means  of  a  detector 
galvanometer  and  a  few  cells.— Connect  this  apparatus  in  series 
and  strike  terminals  quickly  to  see  that  all  is  in  order.  Then 
join  terminals  to  those  of  the  circuit  under  test.  A  deflection 
shows  continuity.  If  there  is  no  deflection  proceed  along  the 
circuit  touching  across  at  convenient  points  with  an  extra  wire 
until  the  break  is  reached. 

IV. — To  measure  an  ordinary  resistance  R  of  a  conductor  "" 
readily  by  the  Substitution  method. — Connect  the  unknown  R, 
a  constant  battery,  a  galvanometer  (shunted  if  necessary)  and  185 
a  key  in  series,  and  note  the  deflection.  Take  out  R  and  insert 
rheostat  or  G.  S.  wire  from  which  throw  into  circuit  a  known  resistance,  r  until 
the  deflection  is  the  same  as  before.  Then,  R  =  r.  Small  resistances  in  G  and 
B  and  a  large  deflection  of  G  are  favorable  conditions. 

(141) 


142 


HANDBOOK   FOR   ELECTRICIANS. 


V. — To  measure  an  ordinary  resistance  x  of  a  conductor  accurately  with  the 
Wheatstone  bridge. — The  Wheatstone  bridge  consists  of  three  sets  of  known 
resistances,  a,  b  and  c,  joined  in  series.  They  and  the  unknown  resistance  x 
form  (for  a  picture)  the  four  sides  of  a  diamond-shaped  figure.  A  galvanometer 
joins  any  two  opposite  points  of  the  diamond,  and  a  battery  the  other  two.  Figs. 
186, 187.  and  188  represent  three  forms,  which  are  lettered  to  correspond.  Two  of 
the  sides  or  sets,  a  and  b,  have  usually  three  coils 
each,  10,100  and  1,000  ohms,  as  in  the  London  P.  O. 
pattern  (fig.  188),  or  consists  simply  of  a  German 
silver  or  a  platinoid  bare  wire,  as  in  the  wire  bridge 
form,  fig.  187.  The  third  set  or  side  has  usually  16 
coils,  so  sized  that  any  resistance  expressed  by  a  3* 
whole  number  between  1  and  11,111  ohms  can  be 
unplugged  from  it.  Any  resistance  between  ^ 
and  1,111,000  ohms  can  be  measured  with  the  Lon- 
don W.  B. ,  and  two  infinity  plugs  permits  its  use 
as  three  separate  rheostats. 

To  measure  with  a  W.  B. — Connect,  as  in  figs. 
186-7-8,  the  unknown  resistance  x,  with  the  three 
sets,  a,  b  and  c,  of  the  bridge  so  as  to  form  a 
simple  closed  circuit.  There  must  be  a  certain 

amount  of  resistance  in  each  set,  the  more  nearly  equal  the  better.  Connect  a 
sensitive  galvanometer  and  key  between  any  two  junctions  not  adjacent  and  a 
battery  and  key  between  the  other  two  junctions. 

While  holding  the  battery  key  Ki  down,  depress  (or  better,  strike)  the  gal- 
vanometer key  K-2.  If  there  is  no  deflection  the  bridge  is  balanced.  If  there  is 
a  deflection,  alter  the  resistance  in  one  or  more  of  the  three  sides,  usually  c,  until 
there  is  no  deflection ;  then  the  unknown  resistance  is  equal  to  the  resistance  in 
c  multiplied  by  that  in  b  and  divided  by  the  resistance  in  a.  Or  x  =  c  X  b  -4-  a. 


186.  Student  Form. 


187.  Workshop. 


188.  London  P.  O. 


VI. — To  measure  a  large  resistance  R  like  the  insulation  resistance  of  a  con- 
ductor by  means  of  a  sensitive  galvanometer  whose  constant  or  deflections  are 
known  and  a  battery  of  known  V. — Detach  the  conductor  from  all  others  and 
guard  against  leakage  at  its  two  ends  over  the  insulation.  Join  in  series  either 
end  of  the  conductor,  G,  V  and  the  frame  or  ground  plate  as  the  case  may  be. 
From  the  deflection  the  current  C  through  the  circuit  is  known.  Then,  R  =  V 
-L-C—G'.  G'  is  small  enough,  relatively  as  a  rule,  or  can  be  made  small  by  a 
shunt,  to  be  called  zero. 

VII. — To  measure  a  small  resistance  R  like  a  piece  of  cable,  joint,  armature 
coil,  etc.,  by  means  of  a  Weston  ammeter  and  voltmeter. — Connect  up  as  in  the 
ov  figure  and  read  the  deflections.  Then  R  =  E  -f-  C. 

r 1  Ex.  When  a  storage  battery,  a  heavy  rheostat  to  prevent 

p«  **  *-*  short-circuiting,  an  ammeter  and  an  armature  whose  resist- 
Oe  *"  ance  was  sought  were  joined  in  series  the  current  was  15  am- 

L,|,|,|,|_I 1  peres<  The  voltmeter  (small  coil)  bridged  across  the  two 

189.  By  Volt  and  commutator  bars  in  contact  with  the  brushes  showed  0.09  volt. 
Ammeter.  jR  of  armature  =  0.006  ohm. 

VIII. — To  measure  the  conductor  resistance  R  of  the  main  or  any  feeder  cir- 
cuit ( lamps  hot}  by  the  switch-board  voltmeter  and  ammeter. — Take  the  instru- 
mental readings  while  current  flows  in  the  circuit  to  be  measured  and  compute 
from  R  =  V  +  C. 


ELECTRICAL   MEASUREMENTS    AND    TESTS.  143 

A  conductivity  test  of  a  main  or  feeder  circuit  with  a  D  G,  or  an  R  measure- 
ment by  the  substitution  method,  will  preclude  all  danger  from  short  circuit 
when  the  feeder  switch  is  closed. 

IX. — To  measure  an,  ordinary  resistance  R  by  means  of  a      H'l'l'l'l' i 

voltmeter  and  a  single  knoirn  rest's  fance  r. — Connect  as  shown          * 

(fig.  190).     If  the  deflection  is  Fwhen  the  voltmeter  leads  are      L1TAAA — wA~l-J 

applied  to  the  ends  of  R  and  v  when  applied  to  r,  R  =  r  V  -r-  v.        I       i 3 

Large  and  nearly  equal  deflections  for  F  and  v  are  favorable      190.  ComparU 
conditions.  son- 

X. — To  measure  a  small  resistance  R  by  means  of  a  voltmeter  and  a  bare 
German -silver  wire  S  of  known  length  and  resistance.— Connect  R,  S  and  a  few 
constant  cells.     Note  the  deflection  F  of  the  voltmeter  when 
its  leads  are  applied  to  the  ends  of  R.     Next  attach  one  lead 

«1'M '     to  the  junction  of  R  and  S  or  the  zero  of  the  length  of  S,  and 

slide  the  other  lead  along  S  until  the  deflection  is  the  same. 
R=tl\e  resistance  readily  computed  of  that  part  of  the  German-silver  wire  between 
the  two  contacts. 

Resistances  between  1  ohm  and  1  megohm  are  usually  measured  by  the  W.  B. ; 
below  1  ohm  by  the  potential  method ;  above  1  megohm  by  the  deflection  method.' 
But  the  substitution  method  being  quick  and  approximate  is  often  used  for  ordi  • 
nary  resistances. 

XL — To  locate  a  short  or  a  partially  open  circuit  (poor  contact}  as  in  an 
armature  by  means  of  the  voltmeter  only. — Send  a  steady  current  through  the 
armature  by  the  brushes  properly  set.  Apply  the  voltmeter  terminals  to  1  and 
2  commutator  bars,  then  to  2  and  3  and  so  forth  on  one  side  of  the  brushes,  and 
in  like  manner  on  the  other.  If  the  deflections  are  all  equal  there  is  no  open  or 
short  circuit.  An  increased  deflection  indicates  a  bad  contact  or  unusual 
resistance ;  a  diminished  deflection,  a  short  circuit. 

Two  or  more  magnet  coils  alike  wound  as  on  fields  or  a  horseshoe,  can  be 
similarly  examined  by  giving  them  the  same  current  and  comparing  the  poten- 
tials of  the  coils. 

XII. — To  test  a  joint,  switch  contact,  battery  connection,  etc.,  by  means  of  a 
voltmeter. — Let  its  maximum  working  current  flow  through  it  and  apply  the  volt- 
meter leads  to  opposite  sides  of  the  joint,  etc.,  and  compare  the  deflection  with 
that  given  by  an  equal  length  adjacent  of  wire  or  bar.  If  there  is  no  deflection 
and  the  voltmeter  is  sensitive,  there  is  no  resistance.  Joints  in  the  same  circuit 
may  thus  be  compared  and  the  loss  of  energy  in  them  may  be  computed. 

If  the  current  U  in  amperes  is  known,  the  resistance  in  ohms  of  the  joint, 
etc. ,  can  be  found  by  R  =  F-=-  C. 

Ex.  A  foot  of  search-light  main  having  a  connection  showed  a  difference  of 
potential  of  TV  volt,  and  a  foot  of  regular  main  showed  ^  volt  while  carrying 
100  amperes.  The  joint  was  a  poor  one.  Its  R  =  0.001  ohm.  Power  lost  in 
joint  alone  =  7  watts. 

XIII. — To  measure  a  large  R,  as  of  insulation,  by  means  of  a  well-insulated 
dynamo  or  battery,  and  a  Weston  two-coil  voltmeter  of  r  ohms  (say  18, 000  Jin  the 
larger  coil.—  Connect  B,  R  and  large  coil  of  voltmeter,  r  (fig.  192).  If  Fis  the 

deflection  when  the  switch  is  closed  and  v  when  it  is  open,  R  =  — H^  r. 

Ex.  The  deflection  on  a  20, 000-ohm  voltmeter  closed  on  a  dynamo  was  100  volts, 
and  in  series  with  the  dynamo  and  unknown  R,  was  40  volts.     R  = 
30000. 

Ex.  The  deflection  by  the  18,000-coil  between  the  poles  of  a  well- 
insulated  storage  battery  was  120,  and  by  the  3-volt  coil  between 
the  extremities  of  the  insulation  R  and  battery  joined  in  series  was          192. 
¥V  volt.    R=Q5  megohms.   R  in  fig.  192  and  in  both  examples  may  be  the  insulation 
resistance  of  a  circuit  whose  conductor  is  joined  at  A  and  a  ground  plate  to  X. 

XIV. — To  measure  the  R  of  a  ground  on  either  leg  of  a  parallel  D.  C.  system 
by  the  above  method. — The  connections  are  made  as  shown  for  an  unknown 

j  j  j  I    ground  on  the  upper  main.     Or,  without  the  switch,  the  volt- 

nil 


f££.vrtauu  uii  uiio  uppcj.   UMNJU.       \ji ,    wii/iiuut    LUC    owiUJU,    LiltJ    VOll- 
•  meter  leads  may  be  applied  first  to  both  mains  to  get  F  and  then 
to  the  lower  main  and  ground  to  get  v ;  whence,  R  =  ( F —  v) 
r  -r-  v  ohms  insulation  of  upper  side.     The  operation  is  similar 
193.  for  finding  the  amount  of  ground  on  the  other  or  lower  side. 

Ex.  The  19, 000-ohm  voltmeter  gave  124  volts  between  dynamo  brushes  and 
4  volts  between  one  main  and  ground.     The  insulation  R  of  the  other  main 
=  (124  —  4)  19000  -*-  4  =  570000. 
If  the  insulation  on  one  leg  is  R  and  on  the  other  R',  the  insulation  of  the 

system  is  1  • 


144 


HANDBOOK   FOR   ELECTRICIANS. 


o 


Ex.  The  insulation  on  the  other  main  in  the  above  example  was  300,000  ohms. 
The  system's  insulation  =  200000. 

If  no  deflection  shows  between  a  main  and  one  ground  there  is  no  ground  on 
the  other  main.  But  if  the  deflection  equals  that  between  mains,  v  =  V  R  =  O, 
the  fault  on  the  other  is  a  dead  ground. 

Every  properly-arranged  switch  board  permits  the  insulation  on  either  side  to  be 
quickly  taken  of  the  whole  system,  or  of  any  feeder  circuit,  or  of  the  dynamo 
alone. 

XV. — To  measure  the  insulation  R  of  the  dynamo  alone,  the  operation  is  simi- 
lar after  opening  the  main  switch.  If  no  deflection  of  a  switchboard,  Weston 
18,000-ohm  voltmeter  between  one  side  and  ground  is  perceptible,  say  ^  volt 
while  the  dynamo  is  running  at  110  volts,  the  insulation  of  the  other  side 
must  exceed  from  XIII,  18000  X  110  X  20  =  40  megohms. 

XVI. — To  measure  the  internal  resistance  R  of  a  dynamo  or  storage  battery 
by  means  of  a  Weston  voltmeter  and  ammeter  as  at  the  switch  board. — Take  the 
potential  V  of  the  generator  on  open  circuit,  and  again  the  potential  v  when 
closed  on  as  many  lamps  as  convenient,  and  at  the  same  time  read  the  current 
C  of  the  ammeter.  R  =  ( V—v)  -=-  C. 

Ex.  The  116  volts  of  58  storage  cells  on  open  circuit  fell  to  115  volts  when 
closed  on  40  lamps  and  the  ammeter  read  20.  R  of  battery  =  ^  ohm. 

XVII. — To  measure  the  internal  R  of  a  battery,  with  a  voltmeter  and  a  kn<>/ni 
r. — Connect  as  in  fig.  194.  Suppose  Fis  the  deflection  when  the 

T7' qj  III 

switch  is  open,  and  v  when  it  is  closed,  R= r  ohms.  |      '  | '  |  ' ) — 

Ex.  Three  Leclanche  cells  in  series  when  connected  directly 
to  the  5-volt  coil  showed  4.5  volts,  and  when  shunted  by  4  ohms 
showed  3  volts.  R  of  battery  =  2  ohms. 

For  a  large  storage  battery  a  heavy  current  rheostat  and  the 
larger  voltmeter  coil  would  be  necessary. 

XVIII. — To  measure  the  internal  resistance  R  of  a  battery  194. 

readily  by  means  of  a  low,  resistance  galvanometer  G,  and  a 
rheostat  r. — Join  R,  O  and  r  (well  plugged)  in  series  and  note  the  deflection 
which  should  be  made  small  by  shunting  G,  if  necessary.     Next  unplug  r  ohms 
from  the  rheostat  until  the  deflection  is  halved.     Then,  R  =  $  r.     Close  the  bat- 
tery for  as  brief  a  time  as  possible  that  its  R  may  not  change. 

XIX. — To  measure  the  resistance  R  of  a  galvanometer  readily  by  means  of  a 
low-resistance  battery  and  a  known  r. — Join  R,  B,  and  r  well  plugged  in  series; 
note  the  deflection  which  should  be  small  by  arranging  the  cells  of  B  in  parallel, 
if  necessary ;  unplug  r  ohms  until  the  deflection  is  halved.  Then,  R  =  -i  r  ohms. 
The  R  of  a  galvanometer  is  preferably  measured  as  an  ordinary  resistance. 

XX. — To  test  the  insulation  R  of  a  conductor  by  means  of  a  magneto. — 
Detach  the  conductor  from  the  rest  of  the  circuit.  Join  one  terminal  of  the 
bell  to  the  conductor  and  the  other  terminal  to  the  ground,  frame  of  instru- 
ment, dynamo,  etc.,  from  which  the  conductor  should  be  insulated.  If  the  bell 
rings  feebly  on  turning  the  crank  the  insulation  resistance  is  less  than  25,000 
ohms,  or  the  capacity  of  magneto.  If  not,  the  insulation  is  greater, 

XXI. — To  select  and  label  the  conductors  of  a  cable. — At  one  end  connect  any 
conductor  (insulated  from  the  others)  to  the  sheathing;  at  the  other  end  connect 
the  sheathing,  a  few  cells,  and  a  detector  terminal  in  series;  tap  rapidly  with 
the  other  terminal  each  conductor's  end  in  turn  until  a  deflection  is  obtained. 
Tag  this  end  and  the  other  connected  with  the  sheathing  as  wire  "No.  1."  In 
like  manner  find  No.  2,  and  so  on. 

A  telephone  receiver  and  a  cell,  or  a  magneto  and  bell,  may  be  used  in  place 
of  the  above  and  a  separate  wire  in  place  of  the  sheathing.  Conductors  can 
likewise  be  selected  at  the  middle  without  cutting  by  piercing  the  insulation 
with  an  ordinary  fine  needle,  which  is  made  the  terminal  of  the  detector. 

XXII.— To  test  for  crosses,  grounds,  and  insulation  of  conductors  in  a  cable. — 
Dry  both  ends  of  the  cable ;  separate  No.  1  for  the  test  from  the  others  at  both 
ends ;  at  the  near  end,  bunch  the  others  to  the  sheathing  and  connect  the  bunch 
in  series  with  two  or  three  cells  and  a  telephone  receiver  post.  When  an  insu- 
lated wire  from  the  other  receiver  post  is  tapped  quickly  on  No.  1,  if  well  insu- 
lated, a  click  will  be  heard  from  a  charge  flowing  to  the  wire,  but  not  at  the 
second  or  third  succeeding  tap.  But  if  No.  1  is  crossed  or  grounded  the  click 
will  be  alike  for  all  taps.  Having  properly  labeled  No.  1,  repeat  the  operation 
on  No  2  withdrawn  from  the  bunch,  and  so  on. 


XVII.— SPECIFICATIONS  FOR  REQUISITIONS,  ALTERATIONS 

AND  REPAIRS. 


IIS"  GENERAL. 

Every  electric  machine  or  piece  of  apparatus  for  war  uses  shall  be  simple, 
certain  in  operation,  proved  in  the  industries  to  be  standard  in  its  class  and  sup- 
plied by  one  of  the  leading  manufactories  in  the  United  States. 

(A)  POWER    HOUSE. 

1.  Located  centrally  and  3  feet  from  protecting  earth  traverse  or  embank- 
ment ;  built  of  brick  or  old  fortification  granite ;  floored  with  concrete ;  roofed 
with  slate  and  iron  in  shed  form  or  with  low  middle  ridge ;  supplied  with  at 
leasx;  five  large,  removable  windows  on  three  sides  and  with  three  large,  window- 
paneled  doors  on  the  front.     In  the  rare  cases  where  the  power  house  can  not  be 
protected,  the  machinery  will  occupy  outer  and  sun -lighted  rooms  only,  of  the 
work. 

2.  Partitioned  laterally  into  (a)  boiler,  (6)  generator,  (c)  battery  rooms. 

(a)  holds  an  inclosed  coal  bin  for  three  days'  supply,  with  outside  chute  at  top 
and  an  inside  shovel  hole  at  the  bottom  accessible  from  furnace  door.  Large 
plants  have  separate  coal  rooms.  Door  permits  horizontal  tubes  to  be  with- 
drawn. There  is  a  ventilator  at  the  highest  point.  For  oil  engines  (a)  holds 
water  tank,  oil  and  supplies. 

(6)  affords  at  least  4  feet  clear  space  around  engine  .and  dynamo  and  in  front 
of  switch  board  facing  dynamo.  Door  between  (a)  and  (&). 

(c)  contains  two  battery  stands  of  two  tiers  or  shelves  each,  solidly  built  from 
one-size  material  (see  "Storage  battery").  They  extend  along  the  lateral  walls 
and  have  5  feet  clear  space  between  them,  or  preferably  30  inches  or  more  clear 
space  on  both  sides.  Distance  between  shelves  =  2  x  height  of  jars.  Ventilators 
at  top  and  bottom. 

(B)  BOILERS. 

A  boiler  is  rated  at  1  horsepower,  which,  with  easy  firing,  moderate  draft, 
ordinary  fuel,  and  good  economy,  can  evaporate  per  hour  30  pounds  (about  \ 
cubic  foot)  of  water  at  100°  F.  into  steam  under  70  pounds  pressure  above  the 
atmosphere. 

1.  For  35  horsepower  or  less,  procure  from  the  standard  factories  only,  verti- 
cal fire  tube ;  for  larger  power  or  as  space  permits,  vertical  or  Hor.  return  fire 
tube  without  dome ;  working  pressure  —  100  pounds ;  water  test  =  150  pounds ; 
safety  factor  =  5 ;  requirements  in  practice  in  chapter  I. 

2.  The  shell  is  of  mild,  nontempering,  open-hearth  steel  plate,  f  to  f  inch 
thick,  having  60,000  pounds  tensile  strength,  56  per  cent  ductility,  20  per  cent 
elongation  of  a  piece  10  by  2  inches  wide.     This  data  and  firm  name  are  stamp'ed 
on  each  plate.     All  holes  are  bored,  not  punched ;  all  joints,  lapped  and  double- 
riveted  longitudinally  and  single-riveted  laterally. 

The  tubes  of  cold-drawn,  seamless  steel,  2-inch  diameter  in  vertical  boilers,  3- 
inch  in  horizontal  and  at  least  i  inch  thick,  closely  fit  holes  drilled  £  diameter 
apart  in  the  clear ;  the  ends  are  expanded  and  flared. 

3.  Length,  one  and  three-fourths  to  two  and  one-eighth  times  diameter; 
capacity  =  one -third  greater  than  maximum  required  by  engine ;  12  square  feet 
heating  surface  per  horsepower  if  boiler  is  vertical ;  15  square  feet,  if  horizontal ; 
36  square  feet  heating  surface  per  square  foot  grate;  one-third  to  one -half  of 
grate  per  horsepower ;  total  tube  opening,  one-tenth  to  one-seventh  of  grate  area ; 
grate  air  passage  =  one-fourth  to  one-half  grate  area ;  chimney  cross  section  = 
one-fifth  of  tube  opening ;  water  feed  —  1  to  H  inch  diameter;  blow-off  =  2  to  2| 
inch  diameter ;  steam  feed  =  engine  opening. 

4.  Interior  braces  and  stays  of  steel  of  60, 000  pounds,  T.  S. ,  not  welded  nor 
worked  in  the  fire,  riveted  and  bolted,  shall  have  such  cross  section  that  the 

H14-10  (145) 


146  HANDBOOK   FOR   ELECTRICIANS. 

strain  (  =  boiler  pressure  X  area  braced  -r-  cross  section)  shall  be  same  as  T.  S. 
above  with  same  safety  factor  and  firm-name  stamp.  Openings,  2  inches  or  larger 
in  the  shell,  shall  be  flanged.  Manholes  or  hand -holes  at  bottom  and  top  shall 
permit  thorough  inspection  and  cleaning.  All  seams  are  calked  inside  and  out. 
Fire  door  has  air  inlet.  Safety  plug  in  tube  is  2  inches  below  lower  gauge  and 
near  a  hand-hole. 

5.  Fittings,  except  pipes,  are  brass. 

(a)  All  piping,  wrought  iron  or  steel,  are  direct  and  short,  with  few  bends 
which  must  have  large  radii,  and  will  be  laid  so  as  not  to  allow  water  to  stand 
in  them.  Steam  pipes  rise  slightly  toward  the  shut-off  valve  next  the  boiler. 
Boiler  and  steam  piping  are  covered  with  asbestos.  No  piping  is  embedded  in 
concrete. 

(6)  Muffled  pop  safety  valve,  with  lifting  handle,  has  1  square  inch  aperture 
to  3  square  feet  grate,  and  opens  at  5  pounds  above  working  pressure. 

(c)  Steam  gauge,  6-inch  face,  has  siphon  and  air  cock. 

(d)  Three  water-gauge  cocks.     Lowest  is  2  inches  above  upper  horizontal 
tubes,  or  one-third  of  the  distance  between  lower  and  upper  flue  sheets. 

(e)  Glass  gauge,  with  two  cut-off  valves,  drain  cocks,  guards,  and  extra  glasses. 
(/)  Blow-off  valves,  with  screw  motion.     Scum  blow-off  cock. 

(g)  Injector,  lifting,  lies  direct  as  possible  between  supply  and  the  delivery 
above  crown  sheet.  Delivery  tube  is  so  bent  that  water  entering  will  flow  with 
the  circulation.  Has  both  check  valve  and  stopcock. 

(h)  Double-acting  suction  and    force  pump  has  air  chamber,   a  branch  in 
suction  for  boiler  compound  and  an  independent  and  straight  connection. 
i)  Feed  water,  heater  and  purifier. 
j )  Steam  separator. 
k)  Exhaust  directible  into  smokestack. 

(C)  GENERATING   SET 

1.  Is  either  a  (1)  standard,  direct-connected,  simple,  steam  engine  and  dynamo 
on  a  common  iron  bed  plate  effectively  grounded,  or  (2)  a  Hornsby-Akroyd 
oil  engine,  link -belt  connected  with  a  standard  dynamo  on  wooden  base  and 
having  an  inertia  wheel. 

(a)  Supplied  by  General  Electric,  Westinghouse,  or  like  standard  company. 

(b)  Stamped  with  name,  volts,  amperes,  power,  speed,  +  and  —  pqsts,  N.  and 
S.  poles. 

(c)  Located  with  switchboard  in  a  dry,  ventilated,  sun-lighted  room  used  for 
no  other  purpose,  and  kept  dry  by  an  oil  stove  if  subject  to  dampness. 

(d)  Bolted  to  concrete  foundations  of  dimensions  given  by  the  makers. 

(e)  Tested  for  two  hours  on  one-third  excess  of  its  full  rated  load  without 
injury. 

(/)  Capable  of  long  runs  on  full  load  without  undue  heat  or  wear. 

(g)  Perfectly  balanced  and  runs  true  without  vibration,  noise  or  leaks. 

(h)  So  efficient  as  to  give  by  ammeter  and  voltmeter  0.80  of  indicator's  power. 

2.  It  requires : 

(a)  A  competent  and  devoted  attendant. 

(b)  At  least  4  feet  surrounding  clear  floor  space. 

(c)  Large  windows  on  two  sides. 

(d)  Full  sets  of  tools,  oilers,  standard  spare  parts. 
'(e)  Full  working  tracings  and  diagrams. 

(/)  If  large,  two  or  more  like  units  with  one  spare. 

(g)  W.  P.  cover  when  not  in  use. 

(h)  Self -oiling  of  all  bearing  surfaces. 

(i)  Means  to  recover  surplus  oil. 

(j)  Guards  to  stop  oil  being  thrown. 

(k)  Metal  can  for  oily  waste. 

(I)  That  oil  shall  not  run  along  shafts  or  spill. 

3.  (a)  Engine,  high-speed,  double-acting,  automatic  cut-off,  simple,  vertical, 
if  30-horsepower  or  less,  horizontal  if  larger,  compound  if  very  large;  to  work 
most  economically  on  80  pounds  pressure  if  simple,  on  100  pounds  if  compound ; 
to  allow,  with  economy,  a  variation  of  20  pounds  either  way  and  fulfill  condi- 
tions on  page  47. 

(b)  The  piston,  rods,  crosshead,  guides,  shaft,  nuts,  bolts,  of  the  best  forged- 
steel,  are  accessible  for  repair,  capable  of  realignment  when  worn  and  strong 
enough  to  allow  sudden  throwing  on  and  off  of  the  whole  load.  The  cylinder 
and  valve  chest,  of  cast  iron  encased  with  nonconductor,  have  relief  valves 
removable  for  indicator  connections. 


SPECIFICATIONS   FOR   REQUISITIONS,    ETC. 


147 


(c)  At  full  pressure  the  governor  prevents  a  variation  lest  than  2|  per  cent  in 
the  number  of  revolutions  during  a  change  from  full  load  to  one-fifth  thereof, 
and  less  than  5  per  cent  for  a  change  of  both  steam  pressure  within  limits  given 
above  and  of  full  load  to  no  load. 

(d)  The  engine  will  have  cylinder,  up-feed  lubricator,  automatic  sight-lubri- 
cation elsewhere,  oil  collectors  and  guards.     The  exhaust,  directible  to  smoke- 
stack and  led  outside  and  concealed,  should  be  killed  if  flowing  water  is  available. 

(e)  Ideal,  Ball,  Straight  Line,  Mclntosh  and  Seymour,  Armington  and  Sims, 
and  Westinghouse  are  names  of  good  engines. 

4.  The  dynamo  is  direct  current,  multipolar,  compound-wound,  and  has  suffi- 
cient potential  to  maintain  during  full  load  and  normal  speed,  110  volts  at  the 
farthest  lamp,  and  to  charge  58  storage  cells. 

(a)  It  requires: 

A  ventilated,  balanced  armature;  a  laminated  core  of  soft-iron  disc  rings; 
P.  D.  between  adjacent  bars  less  than  10  volts;  two  or  more  brush  carbons  in 
each  set ;  rocker  locked  in  any  position ;  large  self  aligning  and  oiling  bearings ; 
field  frame  in  upper  and  lower  halves ;  fuses  on  both  leads ;  vequal  magnetic 
pull  by  all  poles;  all  circuits  of  0.99  cond.  of  pure  cop. ;  a  field  rheostat  by 
same  builder. 

(b)  It  is  capable  of  running  eight  hours  on  full  load,  or  three  hours  on  15  per 
cent  overload,  without  heating  the  commutator  50°  F.  or  any  other  part  40°  F 
above  the  surrounding  air  as  given  by 

a  thermometer  placed  (in  first  case)  on 
the  heated  part  and  covered  with 
waste,  and  in  the  second  case,  3  feet 
from  dynamo  in  line  with  the  shaft. 

(c)  A  change  from  full  load  to  no 
load,  with  brushes  and  rheostat  fixed, 
causes  less  than  2  per  cent  variation  of 
potential  and  no  sparking.     If  the  full 
load  is  suddenly  thrown  off,  the  swing 
of    a    Weston    voltmeter    from    self- 
induction  is  less  than  10  volts. 

(d)  No  insulating  part  can  be  injured 
by  moisture  or  200"  F.  rise  of  tempera- 
ture, and  the  insulation  between  cir- 
cuifcs  or  between  entire  circuit    and 
iron  frame  exceeds  1  megohm  under 
1,000  A.  C.  volt  test  both  before  and 
after  a  run. 

(e)  Armature     windings    must    be 
symmetrical,  systematic  and  replace- 
able;   end    connections,    short    and 
mechanically  made  to  bars ;  wires  hav- 
ing wide  P.  D.  are  kept  apart ;  no  wires 
cross  in  contact  with  each  other. 


195.  Field  Rheostat,  W=e. 
(D)  SWITCHBOARDS. 

Switchboards,  preferably  of  slate,  must  not  carry  anything  which  is  com- 
bustible or  absorptive. 

Be  free  from  moisture,  dust  and  accessible  from  all  sides. 

Have  a  main  switch,  main  cut-out  and  ammeter  for  each  generator ;  a  D.  P. 
switch  and  cut-out  for  each  circuit  leading  from  board  and  a  voltmeter  and 
ground  detector. 

Meet  all  requirements  of  pages  56-7-8. 

Be  wired  as  sufficiently  indicated  on  page  74. 

(E)  STORAGE  BATTERY  (RESERVE  EXCEPT  FOR  MOTORS 

AND  SEARCH  LIGHTS). 

1.  Fifty-eight  chloride  storage  cells  of  about  1  square  foot  positive  plate  (one 
side)  per  12  amperes  of  normal  charging  and  discharging  rate  for  eight  hours 
should  show  85  per  cent  efficiency  and  conform  with  requirements  in  VI. 

2.  The  glass  jars  rest  on  sand  in  wooden  trays  on  glass  or  porcelain  insulators 
on  shelves  of  paraffined  solid  framework. 

3.  Lead-lined  strong  wooden  tanks  are  used  when  plates  exceed  1|  square  feet. 


148  HANDBOOK   FOR   ELECTRICIANS. 

4.  Connections  are  lead-burned,  if  practicable,  or  so  bolted  that  they  allow  no 
greater  drop  than  an  equal  length  of  lead  lug. 

5.  The  jars,  readily  accessible  on  two  sides  if  possible,  should  stand  free  from 
concussion  and  the  direct  rays  of  the  sun. 

6.  Fully  protected  by  an  overload  automatic  cut-out  and  a  D.  P.  switch  near  it. 

7.  Supplied  with  meters  and  facilities  enumerated  in  VI  and  XII  as  necessary 
for  the  care  of  batteries. 

(F)   ELECTRIC  MOTORS. 

1.  All  electric  motors  should  be — 

Furnished  by  one  of  the  leading  manufactories  in  the  United  States. 

Guaranteed  to  meet  the  general  requirements  given  above  for  dynamos. 

Located  in  a  clean,  dry,  well-lighted  place  under  oilcloth  cover. 

Insulated  by  moisture-proof  wooden  base  frame  if  possible ;  else  dead-grounded. 

Slotted  ring  armature;  brush  holder  capable  of  fine  adjustment  and  fixable  in 
the  proper  position. 

Series  wound  (if  hoist),  multipolar  and  having  50  per  cent  excess  of  power. 

If  required,  inclosed  by  frame  against  damp  and  dust.     Hand-holes  have  covers. 

Supplied  with  radial  carbon  brushes,  two  or  more  in  each  holder. 

Constructed  so  as  not  to  spark  between  no  load  and  15  per  cent  overload. 

Fed  direct  through  exclusive  feeders  having  a  cross-section  to  carry  50  per 
cent  excess  of  current. 

Protected  by  rheostat,  overload  and  underload  circuit-breakers,  fuses  and  D.  P. 
knife-switch  within  sight  of  motor. 

2.  Rheostats  to  motors  constructed  of  fire  and  moisture  proof  material  by  the 
builders  of  the  motors,  have  the  overload  and  underload  releases,  usually  attached, 
sufficient  capacity  without  paralleling  coils  and  1  megohm  insulation  R.     The 
contacts  should  be  ample,  the  resistance  such  as  to  drop  the  full  potential  80  per 
cent  at  the  first  point.     Capacity  and  factory  No.  are  plainly  marked.     There 
are  three  types : 

a)  Starting,  capable  of  carrying  line  voltage  15  seconds. 

b)  Regulating,  capable  of  carrying  full  line  voltage  indefinitely. 

c)  Regulating  and  reversing.     C  through  armature  only  is  reversed.      All 
springs  are  of  bronze  and  carry  no  C.     Points  of  control  are  clearly  indicated. 
Rheostats  in  damp  positions  are  inclosed  by  a  water-tight,  fire-proof  case. 

/G)  SEARCH  LIGHTS. 

1.  The  brass  projector,  painted  dead  black  inside  and  out,  holds  the  parabolic 
glass  mirror,  36  to  60  inches  in  diameter,  £  to  i  inch  thick,  and  is  mounted  upon 
a  low  platform  of  a  four-wheel  truck.     Its  arc  can  be  supplied  at  1,000  feet  dis- 
tance from  the  dynamo  through  double  cable. 

2.  The  projector  can  be  directed  by  hand  or  by  means  of  a  controller,  multiple 
cable  and  two  shunt  motors,  so  that  the  beam  can  be  ttirned  to  any  desired  point 
by  a  person  150  feet  away  from  the  projector,  right  or  left,  up  or  down,  in  agree- 
ment with  like  motions  cf  the  controller's  single  handle,  and  with  a  rapidity 
depending  upon  the  amount  of  throw  of  the  handle,  or  with  as  small  motion  as 
desired. 

3.  The  drum  must  be  evenly  balanced,  well  ventilated,  and  fitted  with  peep- 
holes for  watching  and  hand-holes  for  adjusting  the  arc. 

4.  In  all  the  means  of  operation,  in  excellence  of  workmanship,  and  photo- 
metric power,  all  projectors  must  equal  or  excel  the  Schukert  and  General  Elec- 
tric search  lights  of  like  size  manufactured  for  the  United  States  Government  in 
1900,  as  given  on  pages  90-102  of  the  Handbook. 

(H)  INCANDESCENT  LAMPS. 

1.  Sixteen-candlepower  lamps,  with  Edison  short  base,  screw  into  a  brass  out- 
let box  closed  by  a  glass,  screw-rim  globe  (fig.  199)  for  ordinary  use.     For  pow- 
der magazines,  32-candleppwer  lamps  are  clustered  inside  an  air-tight,  moisture 
and  fire  proof  lantern  which  is  placed  in  the  end  wail  nearest  the  gallery  and 
furnished  with  reflector  and  diffusing  lens. 

2.  All  lamps  are  110- volt,  and  of  standard  size  and  make.    Efficiency  =  1  candle 
per  3.1  to  3.5  watts;  useful  life  =  800  hours;  apportion  one    16-candlepower 
lamp  to  1,000  cubic  feet  room  space. 

3.  Filaments  should  stand  centrally  in  a  uniformly  molded  lead  glass  bulb 
without  tip,  have  two  or  three  curls  without  anchor,  and  show  no  dark  or  bright 
spot  when  heated  to  a  dull  red.     The  vacuum  should  allow  no  glow  when  tested 
on  an  induction  coil  delivering  a  ^-inch  spark. 


SPECIFICATIONS   FOR   REQUISITIONS,    ETC. 


149 


4.  The  mean  horizontal  candlepower  obtained  by  revolving  the  lamp  in  a  ver- 
tical position  180  times  per  minute  should  be  within  1  candlepower  of  its  rating, 
and  should  not  fall  below  80  per  cent  of  the  initial  candlepower  after  800  hours'  use. 

5.  Sockets  of  brass,  never  less  than  0.013  inch  thick,  have  solid  construction, 
standard  screw  threads,  porcelain  base,  insulating  lining  fixed,  tough  and  fire- 
proof, and  points  of  opposite  polarity  at  least  -fa  inch  apart,  unless  separated  by 
reliable  insulation.     Except  in  special  cases,  they  are  keyless.     If  suspended,  the 
flexible  cord  enters  the  socket  through  strong  insulating  bushing,  £  inch  inside 
diameter. 

(1)  WIKING. 

1.  The  closet  system  of  two-wire  parallel  distribution  of  direct  current  to 
lamps,  motors,  search  lights,  storage  batteries,  detonators,  etc. ,  afford  the  better 
control  and  protection,  whether  or  not  the  wiring  is  partially  overhead  or 
underground,  or  wholly  interior.  It  takes  more  wire  than  the  tree  system,  but 
allows  switches  and  cut-outs  to  be  safely  and  conveniently  grouped  and  lamps 
to  be  at  more  nearly  equal  voltage. 


196.  Distributing  Current  to  Centers. 

(a)  Feeders  run  from  bus  bars  to  main  centers  in  slate  closets  or  to  motors ; 
mains,  from  main  centers  to  cut-out  boxes  (sub-centers) ;  branches,  from  cut- 
outs to  places  to  be  lighted,  12  or  less  lamps ;  taps,  from  branches  to  lamps. 

(6)     The  route  to  a  lamp  is:  (1)  Bus  bar,  (2)  D.  P.  knife  switch,   (3)  fuses  to 

S-otect  feeder,  (4)  feeder,  (5)  bus  bar  main  center  distribution  box,  (6)  baby 
.  P.  knife  switch,  (7)  fuse  to  protect  the  main,  (8)  main,  (9)  inclosed  fuse  of 
cut-off  box  to  protect  the  branch,  (10)  branch,  (11)  tap  to  outlet,  (12)  snap 
switch,  (13)  lamps. 

(c)  Search  light,  motor,  or  storage  battery  has  its  exclusive  feeder. 

2.  Safety  fuse  cut-outs  are  placed  in  full  view  at  centers  and  subcenters  of 
distribution,  or  where  a  smaller  wire  begins  in  a  parallel  system,  or  where  a 
motor,  battery,  etc,,  requires  protection  from  overload  and  inside  a  building 
where  wires  enter. 

Safety  fuse  cut-outs  are  D.  P.  and  mounted  on  insulating  bases  in  a  small 
dust,  moisture  and  fire  proof  box,  held  out  from  walls  on  porcelains.  Fuse- 
wires  are  in  contact  only  with  their  connections  and  are  f  inch  long  for  50  volts, 
1  inch  for  110,  to  prevent  arcing. 

Cut-outs  require  copper  tips  stamped  with  maker's  initials  and  80  per  cent  of 
the  maximum  C  which  the  fuse  will  carry  indefinitely,  thus  allowing  one- 
fourth  overload. 

Any  set  of  lamps  requiring  more  than  660  watts  should  be  dependent  upon 
more  than  one  cut-out  between  the  lamps  and  dynamo. 

Cut-outs  and  circuit-breakers  are  to  protect  and  switches  are  to  disconnect  all 
circuits  beyond  them. 

3.  Magnetic  circuit-breakers  protect  automatically  dynamos,  motors  and  bat- 
teries against  overload  with  more  certainty  than  fuses,  also  against  underload. 
Both  kinds  must  operate  with  excess  of  power  and  within  5  per  cent  of  adjust- 
ment.    Overloads  are  usually  set  to  open  the  circuit  at  one-half  excess  of  cur- 
rent or  one-fourth  excess  of  voltage ;  underloads,  to  open  at  5  or  10  amperes  of 
current,  or  at  one-fourth  fall,  if  voltage.     They  must  meet  the  requirements  on 
page  61  of  Ite  C.  B's.  (inverse  time  element).     Magnet  iron  parts  are  copper- 
plated. 


150 


HANDBOOK   FOR   ELECTRICIANS. 


4.  Switches  and  circuit-breakers  are — 

(a)  Mounted  on  small  slate,  porcelain,  or  marble  bases,  or  preferably  on  the 
switchboard  when  used  there,  make  sliding  and  secure  contacts,  make  and 
break  rapidly  without  stop  or  spark. 

Carbon-tipped  and  have  threaded  studs  and  flanged  nuts  to  make  back  con- 
nections. 

Stamped  with  words  "on"  and  "off,"  maker's  name,  and  maximum  C  or  V. 


197.  Cabinet  Panel;  Six  Double  Branches,  Six  F.  S.,  One  M.  S. 

(5)  All  conducting  parts  have  such  cross-section  that  heating  from  maximum 
C  can  not  be  felt  by  the  hand. 

(c)  All  switches  are  double  pole;  snap  for  10  amperes  or  less;  knife  for  larger 
but  not  smaller  than  50  amperes ;  in  conduit  not  at  centers,  snap  switches, 
marine  type,  to  50  amperes  may  be  used. 

(d)  Switches  and  cut-outs  are  located,  and  whenever  possible  grouped,  inside  a 
fire  and  water  proof  insulated  box  centrally  located  in  a  dry,  accessible  place 
which  is  free  from  inflammable  material. 


198.  Cabinet  Panel,  Six  Single  Branches,  at  a  Center. 

5.  General  rules  for  wires. — (1)  Coils  purchased  must  show  name  of  manu- 
facturing company,  date  of  manufacture,  maximum  voltage,  and  a  guarantee 
to  be  "National  Electrical  Code  standard. " 

(2)  All  conductors  are  No.  14  B.  and  S.,  single,  and  above  that  size  in  strand 
of  7,  19,  37,  61,  91,  or  127  wires  of  one  size— No.  19,  18,  17,  16,  15,  or  14.     One  of 
a  strand  lies  in  the  center,  and  others,  in  layers,  are  twisted  uniformly  around 
it,  one  turn  in  20  or  30  inches,  adjacent  layers  being  wound  in  opposite  directions. 

(3)  Copper  is  tinned.     No  variation  of  diameter  greater  than  0.002  inch 
allowed. 

(4)  On  poles — H.  D.  copper  with  R.  C.  and  W.  P.  insulation  or  bare  aluminum. 
In  conduit,  ducts  or  on  cleats — soft  copper  of  98  per  cent  conductivity  of  pure  cop- 
per, coated  with  rubber  and  its  compounds  to  a  total  thickness  of  -fa  inch  on  No.  14, 
increasing  with  larger  sizes  to  i-inch  thickness  on  wire  of  1,000,000  c.  m.  or  larger. 

(5)  For  all  rubber-covered  single  concfuctors:  (a)  First  layers  are  of  98  per 
cent  pure  para  rubber,  tough,  elastic,  at  least  ^¥  inch  thick  for  all  sizes,  and 
without  flaws. 


SPECIFICATIONS   FOR   REQUISITIONS,    ETC. 


151 


(7>)  Next  layers  are  vulcanized  rubber  of  40  per  cent  pure  Para,  smooth,  con- 
centric, continuous,  at  least  ^  inch  thick  on  No.  14  increasing  to  /T  inch  on  wire 
of  1,000,000  c.  m.,  and  without  holes  or  flaws. 

(c)  All  layers  of  cotton  tape  thoroughly  impregnated  with  rubber  compound, 
lap  tightly  oiie-half  of  the  width  into  an  even  circular  section  at  least  ^  inch  thick. 

(d)  All  exterior  braid  is  closely  woven  and  thoroughly  saturated  with  an  insu- 
lating water-proof  compound,  uninjured  by  200°  F.  dry  heat,  bending,  or  abrasion. 

(6)  Finished  R.  C.  wires  must  show  an  insulation  greater  than  100  megohms 
per  mile  during  thirty  days'  immersion  at  70°F ;  also  a  dielectric  strength  such 
that  1  foot,  after  seventy-two  hours'  immersion,  will  resist  for  five  minutes  3, 000 
volts  A.  C.  per  ^T  inch  thickness  of  rubber. 

(7)  When  a  cable  has  two  or  more  conductors,  each  is  insulated  with  rubber 
and  taped.     Then  all  are  twisted,  usually  in  layers,  around  the  central  wire,  the 
interstices  often  filled  with  jute,  and  the  resulting  cylinder  is  taped  and  sheathed. 

6.  Interior  conduit . — (1)  All  interior  wiring  is  drawn,  for  protection  against 
moisture  and  injury,  into  low  steel  conduit,  f  inch  to  2£  inches  inside  diameter, 
enameled  outside  and  inside  and  "dead-grounded." 

(2)  Its  lengths  are  coupled  together  like  gas  pipe  and  screwed  into  bronze 
junction,  closet,  switch  and  outlet  boxes  having  close-fitting  doors  or  covers 
which  are  screwed  home  on  rubber  gaskets.     All  ends  of  pipe  are  sealed  up. 
The  lamp  outlet  box  is  closed  by  a  glass  globe  over  the  lamp, 

screwing  against  a  gasket  (fig.  199). 

(3)  To  the  bottoms  of  all  boxes  is  screwed  a  slate  panel,  or 
marble  board,  or  porcelain  block,  which  carries  and  insulates 
the  switch,  fuse,  or  socket. 

(4)  The  conduit  is  either  strapped  to  asphalt-painted  wooden 
cleats,  3  feet  apart,  so  as  to  run  with  all  of  its  boxes  1|  inches 
out  from  ceilings  or  walls,  or  it  is  embedded  in  the  concrete 
2  inches  from  the  surface  of  wall  or  ceiling.     Its  boxes  lie  on 
the  surface  in  the  latter  case. 

( 5 )  The  former  or  exposed  conduit  can  be  painted,  repaired, 
altered,  and  kept  air  and  water  tight. 

(0)  A  good  conduit  system  is  rigid,  continuous,  and  prac- 
tically air  and  moisture  tight  throughout. 

(7)  Rounded  insulated  capping  to  the  ends  of  pipe  inside 
of  boxes  prevents  abrasion  of  the  wire. 

(8)  Great  force  in  drawing  in  wires  is  unnecessary  and 
may  cause  leakage. 

(9)  Both  positive  and  negative  legs  lie  in  one  conduit 

where  either  has  less  than  30,000  c.  m.  conductor;  if  larger,  each  has  a  separate 
conduit.  Clearance  is  Ta¥  inch  at  least. 

(10)  Conduit  wires  require  -fa  inch  thickness  extra  fibrous  covering.    ' 

(11)  Every  length  of 
good  conduit  is  stamped 
with  maker's  name. 

(12)  Snap  switches, 
being  easily  boxed,  may 
be  used  with  conduit  to 
12  amperes. 

( 13)  D.  P. knife  switches 
are  put  in  center  of  dis- 
tribution closets. 

(14)  Wires  are  never 
' '  fished ' '  in  forts.    Flex- 
ible iron  armored  con- 
duit is  permitted  for  re- 
pairs and  "drop  cords." 

(15)  Conduit  is  in- 
stalled and  all  construc- 
tion finished  before  wires 
are  drawn  in.  Bends  have 
4  inches  radius  at  least. 

(16)  After    the    wires  20°-  Exterior,  Wire  Conduit  in  Forts. 

are  drawn  in  the  ends  of  exposed  conduit  and  outlets  are  sealed,  all  joints  of 
pipe  and  boxes  are  painted  with  asphalt  and  precautions  are  taken  to  keep  the 
interior  air-tight. 

7.  Underground  lines. — (1)  Exterior  electric  wires  will,  as  a  rule,  lie  below 
frost,  often  4  feet  underground,  by  being  drawn  into  wrought-iron  pipe  or  glazed 


199.  Water-tight 

Outlet  Box  and 

Glass  Globe. 


152 


HANDBOOK   FOR   ELECTRICIANS. 


clay  conduit  set  in  concrete.     Both  of  these  ducts  connect  manholes  about  250 

feet  apart  and  will  last  indefinitely. 

(2)  Wrought-iron  pipe  duct  (figs.  201-3),  in  20-foot  lengths,  of  3  to  4  inches 

diameter,  £  inch  thick,  dipped  in  tar  to  prevent  rust,  are  jointed  by  a  screw 

coupling,  so  as  to  be  water  and  gas  tight.     The  concrete  is  composed*  of  1  part 

Rosendale  cement  by  volume,  2  parts  sand, 
and  3|  parts  of  broken  stone  passing  H-inch 
mesh ;  is  first  laid  between  l|-inch  planks  on 
the  smooth  bottom  of  the  track  and  rammed 
to  l|-inch  thickness.  Upon  this  is  placed 
the  first  layer  of  pipe,  1  inch  apart,  and  con- 
crete is  rammed  between  them  and  above  to 
H-inch  thickness.  The  process  is  repeated 
until  the  section  is  completed  with  a  2-inch 
plank  cover.  At  a  bend  a  manhole  is  built 
or  the  curve  is  given  a  large  radius. 

(3)  Glazed  clay  conduit  18  inches  long,  3- 
inch  bore,  with  walls  f  inch  thick  and  out- 
side corners  rounded,  are  laid,  breaking  joints 
as  in  fig.  202.  There  is  £-inch  space  between 
the  pipes  of  a  layer  and  bet  ween  layers,  which 
^ ^ is  filled  with  cement  mortar,  while  a  3-inch 

201.  Cross-section  of"iron-Pipe  Conduit,  thickness  of  concrete  mixed  as  above,  sur- 
rounds the  whole.     A  36-inch  mandrel  which 

exactly  fits  the  bore,  preserves  the  alignment  in  laying  the  duct  and  prevents 

mortar  getting  inside.     The  bottom  of  each  18-inch  length  duct  is  slightly  curved 

upward,  so  that  the  joints  may  not  interfere  with 

the  drawing  in  of  the  cable. 

(4)  The  manhole  (fig.  203),  about  3£  by  3|  by  7 
feet  deep  inside,  for  allowing  cable  lengths  to  be 
drawn  into  the  iron  or  earthen  duct  and  for  con- 
necting supply  branches,  is  built  of  brick  and 
made  water-tight.     The  masonry  extends  below 
the  duct  level  to  form  a  catch  basin,  and  is  pro- 
vided at  top  with  a  cast-iron  ring  frame  support- 
ing two  covers,  the  lower  being  screwed  down 
upon  a  rubber  gasket,   and   the    other   resting 
loosely  on  top.     Both  covers  permit  ventilation. 

(5)  For  means  to  draw  in  the  cable,  push  through  a  duct  a  steel  wire,  or  4-foot 
wooden  rods,  jointed,  from  one  manhole  to  the  next.   This  serves  to  pull  through 
a  small  rope,  then  a  large  rope,  then  a  cleaning  steel  scraper  and  brush,  and 
finally  the  cable. 

,    ^      .   -  (6)  Avoid  twist  and  strain  on  the  cable  by 

the  use  of  a  swivel  clevis  attached  to  several 
iron  wires  wrapped  spirally  over  the  first  2 
feet. 

(7)  Specimen  underground  cable  (fig. 
206)  to  be  (a)  No.  14  single  or  larger  con- 
ductor in  strand  of  wires,  uniformly  sized, 
tinned  and  twisted ;  (6)  covered  with  one  or 
more  layers  of  pure  Para  rubber,  tape  spi- 
rally wound,  half  lapping;  (c)  then  coated 
two  or  more  times  with  rubber  compound, 
each  coat  of  two  tapes  laid  on  longitudinally 
and  pressed  into  half -cylinder  forms  which 
unite  in  good  longitudinal  joints ;  (d)  tightly 
bound  with  prepared  rubber  tape  spirally 
wound.  Then  the  rubber  is  vulcanized,  the 
insulation  is  tested,  and  the  outside  tape  and 
braid  or  lead  is  laid  on. 

8.  Overhead  lines. — (1)  Erected    in    forts 
only  where  fully  protected  from  fire  or  for 
203.  Manhole.  temporary  uses. 

(2)  Never  attached  to  trees,  buildings  or  outside  concrete  walls. 

(3)  Wires.—  Hard  drawn  copper,  No.  14  and  larger,  of  60,000  pounds  tensile 
strength,  96  per  cent  conductivity  of  pure  copper  and  tinned,  is  coated  with  /T- 
inch  thickness  of  vulcanized  rubber  and  covered  with  one  or  more  cotton  or 
hemp  braids  saturated  with  moisture  and  fire  repellant ;  bare  aluminum,  58  per 


202.  Clay  Conduit  in  Cement 
Mandrel. 


SPECIFICATIONS   FOR   REQUISITIONS,    ETC. 


153 


cent  conductivity ;  bare  galvanized  iron  in  uninhabited  country  for  signal  pur- 
poses only. 

(4)  In  contact  only  with  double  petticoat  porcelain  or  glass  insulators  and  run 
at  least  1  foot  apart  and  in  such  manner  that  water  can  not  cross-connect. 

(5)  Protected  when  necessary  from  accidental  contacts  with  other  lines  by 
insulated,  dead  guard,  iron  wires. 

(6)  Led  into  buildings  through  noncombustible  insulating  tubes  slanting 
upward  toward  the  inside.     Drip  loops  outside,  safety  cut-outs  inside. 

(7)  Strain  on  wire  for  tying  not  to  exceed  one -third  its  tensile  strength. 


204,  205,  206. 

(8)  Sag  =  1  to  2  per  cent  of  distance  between  poles,  depending  on  extremes  of 
heat  and  cold. 

(9)  Signal  wires  unavoidably  paralleling  heavy  current  lines  are  stretched 
along  lowest  cross-arms.     See  Line  Construction,  page  155. 

(10)  A  lightning-arrester  in  plain  view  is  placed  alongside  of  every  overhead 
line  near  the  point  where  it  has  entered  the  building,  and  is  connected  with  a 
good  ground  (not  gas  pipe)  by  No.  6  copper  wire  direct  as  possible  to  ground. 
A  choke  coil  is  between  arrester  and  dynamo. 

(11)  Poles. — (a)  Wrought-iron  tubing ;  or  wood  of  cedar,  chestnut,  pine,  or 
spruce,  round  or  octagonal,  tapering  to  6  inches  at  top  and  painted.     Galva- 
nizing the  iron  or  creosoting  the  wood  may  preserve  the  poles  thirty-five  years. 
They  are  30  to  60  feet  long,  have  one- 

fifth  to  one -tenth  of  their  length  in  the 
ground,  according  to  soil,  pole  length, 
and  number  of  wires,  and  stand  verti- 
cally in  as  straight  a  line  as  possible, 
125  feet  apart.  Lengths  may  vary  with 


207. 


208. 


the  contour  to  keep  the  line  more  nearly  straight.  At  unavoidable  curves 
heavier  poles  are  inclined  outward,  guyed  or  double -guyed  laterally  on  the 
outside  by  strands  of  No.  6  or  8  galvanized  iron  from  beneath  the  single  cross- 
arm,  or  the  middle  of  the  lower  half  of  several  cross-arms  to  a  guy  stub  or 
anchor,  or  they  are  braced  on  the  inside  by  a  half  pole,  solidly  planted  and 
bolted  at  30°  angle  with  the  pole. 

In  raising,  two  spikes  may  replace  the  ladder;  the  "dead  man"  holds  what- 
ever is  gained  in  raising. 

(6)  Cross-arms  of  iron  are  clamped;  of  clear  yellow  pine  or  oak  wood  are 
bolted  (fig.  208)  into  gains  cut  in  the  poles,  braced  with  iron  and  spaced  as  shown. 
The  pins  are  of  locust. 


154  .  HANDBOOK   FOR   ELECTRICIANS. 

(c)  Guys  of  iron  strand  are  put  laterally  on  every  tenth  pole  of  a 
straight  line,  on  all  poles  from  which  service  wires  lead  to  either  side, 
and  longitudinally  on  the  two  poles  of  an  unusually  long  span  and 
the  two  or  three  end  poles  of  every  line. 

(12)  Insulators  of  porcelain  or  blown  glass,  subject  to  not  less  than 
a  6,000-volt,  5-ampere,  break-down  test,  have  the  two  or  three  petti- 
coat form,  and  are  screwed  to  iron  or  oak  pins  which  are  bolted  or      209 
screwed  to  the  cross-arm. 

(J)  ITEMS  NOT  PREVIOUSLY  SPECIFIED, 

(Brackets  refer  to  manufacturer. ) 

Annunciator,  index  or  gravity  drop. 

Anti-hum,  Clarke. 

Arc  lamp,  inclosed  [G.  E.  ] . 

Babbitt  metal,  "Best." 

Bases,  porcelain  of  all  kinds  [G.  E.]. 

Bell,  single  stroke,  "Vigilant"  or  "Covered." 

Bell,  vibrating,  dust  and  water  tight  [W.  E.]. 

Binding  post,  English  [W.  E.]  or  Nos.  1,  2,  and  connectors  [Mn.]. 

Boards  (panel),  marine  type  [W.  E.]. 

Boxes  (junction,  outlet,  switch),  iron-armored  or  marine  [W.E.]. 

Buzzer,  Eco  or  Lungen. 

Call  box,  Firman  with  Ans.  back  [B.]. 

Clamp,  Klein  or  "parallel." 

Conduit,  iron -armored  insulating  [W.  E.]. 

Connectors,  Mclntire. 

Cut-outs,  bases,  receptacles  [G.  E.J. 

Drill,  hand,  hollow  handle  [W.  E.J. 

Gong,  clock  to  60  strokes,  marine  [W.  E.]. 

Gauge,  calculating  U.  S.  Wireman's  [Mn.]. 

Gauge,  caliper,  Micr.  0.001  to  0.5  inch  [Mn.]. 

Instruments,  portable,  Weston. 

Insulators,  glass,  2  or  3  petticoat. 

Insulators,  porcelain,  F.  H.  screw  or  G.  E.  knob. 

Junction  box,  iron-armored  or  marine. 

Lamps,  incandescent.  Navy  [G.  E.]. 

Pliers,  Stubs  or  "Universal"  [Mn.]. 

Push  button,  plain,  bronze,  water-tight. 

Receptacle,  water-tight  [G.  E.]. 

Rheostat,  Carpenter. 

Socket,  lamp,  marine  [G.  E.]. 

Soldering  torch,  gasoline,  Imperial  or  Wellington. 

Soldering  furnace,  "Combination"  or  "  Universal." 

Speed  indicator,  Starrett. 

Switch  (in  closet  or  on  switch  board),  knife  [G.  E.,  W.  E.,  or  Mn.]. 

Switch  (in  conduit)  snap,  D.  P.,  marine. 

Switchboard  (dynamo or  battery)  [G.  E.,  W.  E.  or  E.  S.  B.]. 

Switchboard,  telegraph  or  telephone  [W.  E.  ] . 

Telegraph  instruments  [Bunnell] : 

Key,  steel  lever,  solid  trunnion,  with  or  without  legs. 

Key,  cable,  on  rubber  base. 

Relay,  Western  Union. 

Relax,  box  and  key  combined. 

Relay,  pocket,  nickle-plated  [W.  E.]. 

Relay,  polarized,  armature  lever  vertical. 

Register,  ink,  self  starting  and  stopping,  one  or  more  pens. 

Set,  polar  duplex,  W.  U 

Set,  quadruplex,  W.  U. 

Testing  set,  magneto  to  ring  through  50,000  ohms. 

Tool  handle,  "Cocobolo." 

Tool  handle,  eleven  tools  [W.  E.]. 

Voltmeter,  recording,  Bristol's. 

Wheatstone  bridge  [W.  E.  or  Biddle]. 


SPECIFICATIONS   FOR   REQUISITIONS,    ETC. 


155 


(K)  RUXES  GOVERNING  JLIXE  CONSTRUCTION. 

9.  (1)  Small  conductor  resistance,  large  insulation  resistance,  order,  perma- 
nency and  accessibility  characterize  good  wiring.  To  wire  neatly  and  effec- 
tively is  an  art. 

(2)  Wires  which  are  separately  insulated  run  at  least  1  inch  apart,  parallel  if 
in  the  same  direction,  straight  between  the  fewest  possible  insulators,  in  contact 
with  insulators  only,  and  in  such  a  way  that  no  two  wires  can  ever  touch  each 
other. 

(3)  Avoid  temporary  work;  in  construction  regard  all  other  wires  as  "live" 
and  bare. 

(4)  If  a  kink  or  a  nick  occurs  in  the  conductor,  cut  it  out.     If  the  insulation 
gets  damaged,  paint  and  tape  the  conductor  as  in  jointing. 

(5)  In  cutting  a  wire,  grip  it  with  the  cutting  jaws  of  the  pliers  so  moved  as 
to  cut  an  arc  of  a  circle.     Twisting  breaks  the  knife  edge.     Then  grip  the  wire 
with  the  flat  jaws  close  to  the  cut  and  one  or  two  sharp  twists  will  give  a  square 
break. 

(6)  Avoid  "come  alongs"  or  vises  when  they  tear  the  insulation,  but  take  a 
series  of  half  hitches  or  noose  wrap  with  a  small  rope. 

(7)  Jointing  electrical  conductors  is  of  hourly  occurrence  and  requires  the 
care  and  skill  acquired  only  by  practice. 


210,  211. 

(a)  Joints  in  copper  or  aluminum  lines  are  often  made  with  the  Mclntire 
(fig.  210)  connector.  The  two  ends  brightened  are  slipped  from  the  opposite 
directions  into  the  close-fitting  double  sleeve  which  is  then  twisted  by  special 
pliers.  Solder  the  ends  only  to  avoid  annealing  the  main  line  and  smooth  down 
projecting  parts  which  might  pierce  the  insulation. 

(&)  The  lineman's  splice  (fig.  212)  for  galvanized  iron,  sometimes  for  soft  cop- 
per, is  made  by  holding  the  two  cleaned  ends  at  an 
angle  in  a  hand  vise,  and  twisting  with  pliers  by  half 
turns  each  end  in  succcession  five  times  closely  around 
the  line  and  soldering. 

(c)  All  joints  of  insulated  wire,  after  being  cleaned  and  thoroughly  dried,  are, 
as  a  rule,  alternately  painted  with  a  thin,  uniform  coat  of  rubber  or  other  solu- 
tion, and  wound  with  tape  half  lapping.     Each  winding  is  a  little  longer  than 
the  one  before  it  and  runs  oppositely.     In  stripping  insulation  to  make  a  joint, 
cut  as  in  whittling  toward  the  ends  into  a  lead-pencil  shape.     For  special  wires 
follow  the  manufacturer's  directions  in  jointing. 

(d)  The  ends  of  a  strand  are  separately  joined  by  a  twist  or  a  connector,  as 
above,  in  places  not  opposite,  to  avoid  too  large  a  bunch  when  finished.     Then 
paint  and  tape  alternately. 

(e)  The  ends  of  a  large  solid  core  are  beveled  and  notched  for  at  least  1  inch, 
then  soldered  together  into  a  round  piece  of  the  same  diameter  as  the  conductor, 
then  wrapped  closely  with  fine  copper  which  is  also  solidly  soldered,  and  the 
whole  is  finally  taped.     The  finished  insulated  joint  is  considerably  larger  in 
diameter  than  the  cable. 

(/)  Insulating  joints — Carefully  cut  the  ends  of  the  insulation,  and  clean 
with  a  little  benzole.  Rub  a  little  rubber  solution  over,  and  then  carefully 
wind  spirally  over  the  joint  and  tapered  end  of  the  insulation,  pure  rubber  tape. 
Cover  this  with  rubber  solution  and  wind  on  more  until  the  diameter  of  joint 
is  about  the  same  as  the  rest  of  insulation.  Over  this  and  for  about  two  inches 
on  each  side  of  the  cut  ends  of  the  insulation,  wind  especially  prepared  braid- 
ing. Finally  varnish  the  whole. 

(g)  Vulcanized  rubber  joints. — Cover  joint  with  pure  rubber  strip.  Rub  in 
some  special  rubber  solution,  allow  to  dry,  bind  with  valcanizing  rubber  tape 
three  or  four  layers.  Then  with  prepared  rubber  tape  cover  the  whole  with  a 


156 


HANDBOOK   FOR   ELECTRICIANS. 


piece  of  strong  silicia  cut  to  length  of  joint  and  then  rolled  round  it,  having  a 
longitudinal  seam.  Bind  this  with  strong  cotton  selvedge  tape.  Joint  is  now 
ready  for  the  cure,  which  consists  in  subjecting  it  for  half  an  hour  or  more  to 
the  action  of  molten  sulphur,  the  joint  being  placed  in  a  specially  made  box  for 
the  purpose.  Molten  sulphur  is  run  out,  and  joint  cooled,  the  outer  wrapping 
of  silicia  and  cotton  removed  and,  if  the  vulcanizing  is  satisfactory,  the  joint  is 
finished  by  braiding  and  varnishing. 

(h)  Most  large  cables  and  special  makes  have  specially  designed  mechanical 
joint  boxes.    • 

(i)  Make  as  few  joints  as  possible.     Solder  all  joints  or  other  surfaces  perma- 
nently in  contact. 

(j)  Solder  is  to  prevent  rust  between  the  wires  of  a  joint ;  acid  for  cleaning,  or 
a  flux  will  later  cause  rust.  Therefore  use  resin. 
Use  the  soldering  iron  for  small 
wires  and  dip  the  large  wires  in 
molten  solder  or  pour  on  with 
a  ladle.  In  all  cases  avoid  burn- 
ing the  insulation. 

(k)  Work  with  clean  hands  in 
insulating  a  joint.     If  the  tape 
gets  burned  or  dampened  or  dirtied,  cut  the  piece  out  and  begin  again. 

(8)  A  standard  tie  is  made  by  a  short  length  of  tie  wire,  bare  or  insulated  like 
the  main,  but  one  or  two  numbers  smaller.     Fig.  213  is  for  galvanized  iron ;  fig, 
214  is  for  H.  D.  copper  main,  which  should  not  be  bent. 

(9)  A  lightning  rod  of  No.  6  bare  galvanized  wire  extends  from  1  foot  above 
the  top  of  every  tenth  pole  to  a  few  hand  turns  of  the  wire  buried  at  its  foot. 


214. 


INDEX. 


Page. 

BATTERIES,  PRIMARY 114 

Amalgamating  zincs 114 

Bichromate 117 

Care  of 114 

Cells,  how  joined 115 

Copper  oxide 116 

Current  weakens 114 

Directions,  general 114-5 

Dismounting 116-7 

Dry 115 

Eagle 116 

Gravity 115 

Fuller 117 

Kinds  of 115 

LeClanche 115 

Local  action 114-7 

Maintenance 115-6-7 

Management 114 

Mounting 115-6-7 

Polarization 114 

Principles 114 

Qualities  of  good 115 

Room 114 

BOILERS,  STEAM 7 

Banking  fires 8 

Blow-off 10 

Care  of 8 

Cleaning 13 

Cleaning  fires 8-9 

Corrosion 13 

Explosions 14 

Feed  water 13 

Firing 7 

Fittings 9 

Foaming 8 

Gauge  glass 10-17 

Incrustation 13 

Injector 12 

Inspection 13 

Low  water 8 

Lying  idle 9 

Management  of 8 

Material 9 

Piping 9,47 

Plug,  fusible 10 

Pressure  gauge 10-13 

Priming 8 

Pump 10 

Safety  valve 9 

Steam  gauge 8 

Tools 7 

DYNAMOS,  D.  C 49 

Armature 43-4-6,  51-2 

Bars 45 

Bearings 45,  52 

Brush  holder 49,  50 

(157) 


DYNAMOS,  D.  C.— Continued. 

Brush  setting 50-3 

Care  of 53-5 

Coils,  armature 44 

Commutator 42-5,  50-3 

Compounding 49 

Core,  armature 44 

Diseases 52 

Drum 43-4 

Failure  to  generate 53 

Field,  magnetic 42 

Field,  windings 45 

Foundations 47 

Fuse  firing 46 

G.  E.,  D.  C.  sets 47 

Generates  alternating  C 42 

Governor 48 

Heating 52-5 

Induction,  laws  of 42 

In  parallel 51-4 

Inspection 53 

Management  of ._    53 

Lap  winding 43-4-5 

Lead 55 

Noise 52 

Oil  rings 45 

Packing 49 

Piping 47 

Pressure 47 

King  winding 43-4 

Running 47,  54 

Self-exciting 43 

Special  service 46 

Speed 47-8,  53 

Spools 49 

Starting 51-4 

Steam  pipes 47 

Stopping 55 

Telephone  call 46 

Tested 47,  51-2 

Troubles 52 

Valves,  relief 48 

Wave  winding 43-4 

Westinghouse  (fig.  74) 72 

Windings 45 

ENGINE,  OIL,  H.-A 29 

Air  inlet 34-8 

Alterations,  fundamental 39 

Crank  positions 35 

Critical  positions 29 

Cycles 29 

Cylinder 29,38 

Exhaust 34-8 

Failure  of 36 

Fly  wheel 36 

Governor 27,37 


158 


INDEX. 


Pa-.'. 

ENGINE,  OIL,  H.-A. — Continued. 

Governor  bracket 36 

Ignition  retarded 38,41 

Indicator  cards 29,41 

Instructions  for 35 

Lamp,  heating 35 

Oiling 36-9 

Oil  tank 38 

Nomenclature 31 

Piston 35-8 

Piston's  strokes ^ 29 

Port 35 

Principles  of 29,31 

Pump 34-6 

Regulation 34-7-8 

Bunning 37 

Skew  wheel 39 

Spray  hole 38 

Starting 35-6 

Starting  gear 36 

Stopping -    39 

Strokes 29 

Testing 40 

Valve  box 34-7-8 

Valve,  horizontal 34-8 

Valve,  vertical 34 

Vaporizer 29,35-6-8 

"Water  supply 

Works  well 39 

ENGINE,  STEAM 16 

Adjustments 17-23 

Angle  of  advance 18,20-22 

Bearings 25 

Care  of 17 

Clearance 25 

Connecting  rod 25 

Crank 17 

Cross-head 25 

Cut-off 19,22 

Dead  center 23 

Eccentric  arm 20-2 

Exhaust 17 

Full  port 18 

Governor 22-7-8,48 

Heating 17-8 

Inspection 23 

Knocking 17 

Laps 18 

Lead 18 

Level 23 

Lining  up 23 

Lubricator 18 

Management  of 17 

Oil 17 

Operation 16 

Packing 17,25,49 

Piston,  fit  of 23 

Piston  strokes 17,21 

Piston  valve 27 

Pressure 47 

Positions,  critical— 20 

Kunning 16, 51 

Slide  valve 25 

Speed 47-8 

Starting 16, 51 

Stopping 16 

Strokes,  piston 17,21 


Page. 

ENGINE,  STEAM— Continued. 

Testing 23, 47 

Travi-1,  piston's 18 

Valve's  positions 18,20 

Valves,  relief 48 

Valve  slide -2.', 

HOIST  AMMUNITION 88 

Automatic  safety  stop 88 

Connections 89 

INSTRUCTIONS,  SPECIAL 5 

Directions,  printed 5 

Text  books 6 

MEASUREMENTS  AND  TESTS 141 

Apparatus  required 141-2-4 

Armature  resistance 142 

Battery  resistance 144 

Cable's  insulation 144 

Care  of  instruments 141 

Conduction  resistance 141-2 

Connections 143 

Continuity  of  circuit 141 

Current  strength 141 

Crosses 144 

Difference  of  potential 141 

Dynamos 144 

Electromotive  force 141 

Galvanometer  resistance 1 144 

Grounds 143-4 

Insulation  resistance 142-3-4 

Joints 142-3 

Magneto 144 

Open  circuit 143 

Besistance,  battery 144 

Besistance,  conduction 141-2 

Besistance,  insulation 142-3-4 

Besistance,  small 142-3 

Besistance,  ordinary 141-2-3 

Storage  battery,  resistance 144 

Telephone,  use  of 144 

Wheatstone  bridge 141-2 

LAWS,  EXAMPLES,  TABLES 135 

Bridge  wire,  table 137 

Capacity 135 

Cells,  combined 136 

Copper  wires,  table 137 

Current,  strength 135 

Difference  of  potential 135 

Direction  of  current 135 

Divided  circuit 136 

Electromotive  force 135-6 

Equivalents 135 

Examples 138-140 

Feeder,  sizes 139 

Formula,  general 138 

Fuses,  sizes 138 

Gauge,  wire 137 

Heat 135-6 

Kilowatt 135 

Metal  deposited 137 

Ohm's  law 135-8 

Power 135-7 

Quantity 135 

Resistance 135-6 

Safety  fuses 137 

Sizes  of  wires 138-9,140 

Table,  wiring 137 

Taps 138-9 


INDEX. 


159 


Page. 

LAWS,  EXAMPLES,  TABLES— Continued. 

Underwriters'  table 137 

Units 135 

Wires,  copper 137 

Wire,  size  of 137-8-9 

MISCELLANEOUS 109 

Anemometer 112 

Battery,  firing 110 

Bells,  electric 111 

Care  of  anemometer 113 

Connections 110 

Detonator 111 

Dynamo,  firing 110 

Failure  to  fire 110 

Firing  battery '110 

Firing  key 109 

Fuses 109,110 

Mechanism 111-2-3 

Mine  charge 110 

Mine  fuse 110 

Placing  the  fuse 110 

Precautions  in  firing 111 

Pressure,  wind 113 

Self-register 112 

Stop-clock 112 

Velocities  of  wind 113 

Wiring 111 

MOTORS,  ELECTRIC,  D.  C 78 

Adjusting  rheostat 81-3 

Back  E.  M.  F 78 

Blow-out  (figs.  107-8,110) 82-3 

Booster 87 

Care  of 84 

Compound L.     80 

Connections 80-3-5 

Controller 88 

Cores _ 79 

Direction  of  rotation 78 

Dynamotor 86 

Electric  hoist 88 

Efficiency  of 78 

Heating 85 

Hoist,  electric 88 

Installing 83 

Leonard  85 

Management  of 84 

Motor  generator. 86-7 

Multipolar  (fig.  118) 78-9 

Overload,  C.  B 83 

Principles 78 

Protection  to 80 

Regulation . 80 

Reversing . 85 

Rheostat,  S.  and  S.  (figs.  109,  110) 80-1 

Rheostats,  installing 83 

Running 84 

Shunt 79,  82-3 

Series 79,  81-5 

Special  forms 85 

Special  uses 79 

Starting 84-5 

Starting  box 80 

Stopping 85 

Switch 83 

Teazer  system 86 

Underload,  C.  B 83 

Watt-hour  meter.__  _    85 


Page. 

MOTORS,  ELECTRIC,  D.  C. — Continued. 

Westinghouse  (fig.  118) . 87 

Winding 79 

NKJHT-SKJXAL  SETS 103 

Assembling 106 

Boughton  set 106 

Cable 103-5-6 

Connections 103-5-6 

Controller,  trucklight 107 

Keyboard  (fig.  137) 103-6 

Ladder 104 

Lanterns 104 

Mechanism 103 

Operation 104-8 

Packings 105 

Plug ___  104-5 

Receptacle 104-5 

Switch,  controlling 107 

Truck  light _•  106 

U.  S.  form 106 

Wiring 103-5-6 

SEARCH-LIGHT  PROJECTORS 90 

Arc 98 

Automatic  feed 95 

Base  sheeting 97 

Beam 91-2 

Cable 98,101 

Carbons 90, 91-4-6 

Carbon  holders 93 

Carboning  lamp 93-5 

Care  of  lamp 94-5-6, 101 

Connections 97-8-9,100 

Controlled 91 

Controller  (fig.  123) . 97-8 

Couplings 102 

Covers 102 

Crater 95 

Current 91 

Dead  resistance 99 

Diagrams 130-1-2 

Drum 91 

Feeding _, 91-6 

Field  (figs.  135-6) 102 

Flaming 96 

Front  door 92 

Focusing  lamp 94 

General  Electric  Co.'s 90 

Hand  control  (fig.  133) 90 

Hissing 96 

Illumination 102 

Image  of  arc 94 

Installing 92-7-9 

Lamp  mechanism  (figs.  124-7-8) 93 

Largest  size 102 

Location 102 

Mechanism  (fig.  124) 95-7-8-9 

Methods  of  observing 102 

Mirror 101 

Motors 97-8 

Mushroom 96 

Names  of  parts 92-3-7 

Navy 90 

Observers 102 

Operating 101 

Operating  lamp 93-4-5-6 

Operators 102 

Parabolic  mirror_._  __  90-2 


160 


INDEX. 


SEARCH-LIGHT  PROJECTORS — Continued. 


Page. 


Pilot-house 91 

Placing  lamp 93 

Probability  of  injury 102 

Rheostat 9Q 

Schukert  (fig.  120) 90 

Screen  shutters 91 

Signaling  with 102 

Small  motion 101 

Speed  of  control 92 

Sizes 90 

Starting  magnet 94 

Striking  the  arc 96 

Switch  controller 98 

Training  mechanism 98 

Transportable 102 

Truck  92 

U.  S.  form  (fig.  123) 92 

Voltage 95-6,101 

Wiring 94-6-8-9, 100 

SPECIFICATIONS 145 

Armatures 147,43-4-6,51 

Battery  room 145,65 

Blow-off 146, 16 

Boilers 145, 7 

Cabinets 150 

Cables 152 

Circuit  breakers 149,150 

Closet  system 149 

Conduit 151-2 

Construction  of  lines 154 

Cross-arms 153 

Cro-3shead 145,  25 

Cut-outs 149,  57-8 

Deadman 153 

Duct 152 

Dynamo 146-7,  47 

Dynamo  room 145,  48 

Engine 146-7,  16 

Feeders 149 

Filament  lamp 148 

Fuses 149,  109 

General  rule  in  specifications 145 

Generators 146-7,  47 

Governor  engine 147,  2-7-8 

Guides 146,  23-4 

Guys 154 

Injector,  eteam__ 146,  12 

Insulating  joints 155 

Insulators 154 

Items,  miscellaneous 154 

Joints  155 

Lamps 148 

Lightning-arrester 153 

Lightning  rods 156 

Lubricator 147,  18 

Mandrel 152 

Miscellaneous  items 154 

Motors 148,  78 

Outlets 151 

Overhead  lines 152 

Piping 146,  152,  9 

Piston  rod 146 

Poles 153 

Power  house 145 

Projectors 148,  90 

Pump 146 


Page. 

SPECIFICATIONS — Continued. 

Rheostat,  motor 148 

Safety  valve 146,  9 

Search  lights 148,  90 

Shaft 140 

Sockets,  lamp 149 

Solder 156 

Steam  gauge 146,  8 

Storage  battery 147,  65 

Switchboard 147,  56 

Switches 150-1,  57,  61 

Ties 156 

Underground  lines 151-2 

Vulcanizing  rubber 155 

Wires 150-1-2 

Wiring 149, 151-2-3 

STORAGE  BATTERY 65 

Back,  E.  M.  F 68 

Battery  room 65 

Buckling 76 

Booster  connection 75 

Care  of 67 

Charge  of 67 

Charging,  initial 67, 76 

Connecting  up 66, 74-5-7 

Current 6T 

Density  of  solution 67-9 

Discharge 69 

Drop  in  voltage 69 

Electrolyte 66-8-9, 71-2 

End  cells 62-4-8 

Endurance 76 

First  charge 66 

Gassing 68, 71 

Good  condition 66 

Inspections 70-1 

Instructions 67 

Instruments 69, 74-5 

Jars 65 

Maintenance 70 

Management  of 67,70 

Maximum  rate 67 

Mixing  solution 70 

Object  of 65,76 

Out  of  commission 72 

Polarity 77 

Portable 76 

Records 71-2-3 

Restoration 68 

Room 65 

Sediment 70-1 

Separators 66 

Setting  up 65 

Shipment 6a 

Specific  gravity 67-8-9 

Stand 65 

Sulphating 76 

Switchboards 74-5 

Temperature  effects 67 

Unpacking 65 

Voltage 67-8-9 

SWITCHBOARDS - 56 

Ammeter 56, 60 

Apparatus 56, 60 

Arrangement 56 

Back  connections 61 

Best  for  forts  __.  -    56 


INDEX. 


161 


Page. 

SWITCHBOARDS — Continued. 

Care  of 64 

Circuit  breakers 57-8 

Conditions  fulfilled 56 

Connections 56 

Design 56 

End  cells 02-4-8 

Engineer 57-8-9 

Fuses 61 

Golden  Gate  board 63 

Key  West  board 62 

Location 56 

Management  of 64 

Overload,  C.  B 57-8 

Operation  of 64 

Panel 56 

Preble  board 62 

Switches 57,61 

Underload,  C.B 57-8 

Voltmeter 56-7 

TELEGRAPHY I__  118 

Abbreviations 119,121 

Adjustments 119, 120 

Beginners 120-1 

Breaks 122 

Care  of 120-4-6-7 

Code  118-9,121 

Code,  artillery 122 

Code,  calls 121 

Code,  signal 121 

Dash  118 

Diagrams 118,120-1 

Directions 120 

Dot 118 

Escapes 123 

Faults,  line 123 

Fog,  signals 122 

Heliograph 122 

Installing 126 

Instructions  120-1 

Key 118, 120 

Lantern 121 

Lineman 123 

Management 124-6 

Message  forms 119 

Morse 118 

Operation 124 

Principles  telautograph 123 


Page. 

TELEGRAPHY — Continued. 

Receiving 120-1-2 

Relay 118,  120 

Searchlight 121-2 

Sending 120-2 

Setting  up  heliograph 122 

Signal  flags 121 

Sounder 118 

Space,  signal 118 

Sticking 120 

Telautograph 123 

Torch 121 

Transmitter  (fig.  167) 123-5 

Wigwag 121 

TELEPHONY 128 

Adjustments 131 

Apparatus 128 

Battery 131 

Bell,  polarized 128,  130-1 

Bridge 128 

Care  of 130-1 

Central  station 133 

Common  battery 132 

Connections 128-8 

Cross-talk 131 

Details 128 

Drops 133-4 

Dynamo 46 

Faults 130-1 

Handling 130 

Holtzer  Cabot 132 

Induction 131 

Intercommunicating 131 

Jacks 134 

Keys 133 

Magneto 46,128,131 

Management 130 

Number  on  circuit 130 

Noises,  induction 131 

Parallel  connections 131 

Receivers 128, 131 

Secondary  coil 128 

Series  connections 128 

Transmitter 128, 131 

Troubles 130 

Using 130 

Without  central ._  132 


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